Carbon-neutral methane management system

Abstract

A carbon neutral methane management system (1) used for a grid for supplying, to a user, mixture gas including city gas and carbon neutral methane (hereinafter, denoted as CN-CH4) comprises: a calculation processing unit (13) calculating the amount of heat generated from the mixture gas in the grid; a supply utilization control unit (12) providing an instruction for adjusting at least any of an amount of city gas supplied to the grid, an amount of city gas utilized by the user, an amount of CN-CH4 supplied to the grid, and an amount of CN-CH4 utilized by the user so that the amount of heat generated from the mixture gas is within the restriction of the grid; and a certificate issuance unit (11) issuing a certificate which proves that the amount of CN-CH4 supplied by a CN-CH4 supplier to the grid is the supply amount of CN-CH4 after adjustment by the supply utilization control unit or a certificate which proves that the amount of CN-CH4 utilized by the user is the utilized amount of CN-CH4 after adjustment by the supply utilization control unit.

Description

Technical Field

[0001] The present invention relates to a carbon-neutral methane management system that utilizes and operates carbon-neutral methane in an existing urban gas grid.

Background Art

[0002] In recent years, the momentum to prevent global warming has been rapidly increasing. Many developed countries have declared carbon neutrality by 2050 and are promoting decarbonization as a national strategy. In Japan as well, in October 2020, a "Declaration of Carbon Neutrality by 2050" was announced, declaring the realization of a decarbonized society by 2050 and substantially zero emissions of GHG (Greenhouse Gas).

[0003] Furthermore, the Ministry of Economy, Trade and Industry formulated a "Green Growth Strategy" towards carbon neutrality in 2050 (hereinafter referred to as CN) on June 18, 2021. In the Green Growth Strategy, implementation plans were formulated for 14 important fields expected to grow, setting high goals as a country and showing as specific a perspective as possible from both aspects of industrial policy and energy policy.

[0004] In the "Next-generation Thermal Energy Industry", which is one of the 14 important fields, the goal is to carbonize urban gas by 2050. As steps towards this goal, injecting 1% of carbon-neutral methane (hereinafter referred to as CN-CH4) into the existing gas grid by 2030 and injecting 90% of CN-CH4 by 2050 are set as milestones.

[0005] CN-CH4 refers to synthetic methane obtained from carbon dioxide (CO2) recovered from exhaust gases in the industrial and power generation fields, the atmosphere, etc., and hydrogen (H2) produced from renewable energy (hereinafter referred to as renewable energy) or biomass, or biomethane produced by fermenting organic waste such as food waste and livestock manure. Synthetic methane is obtained by the reaction of the following formula (1). CO2 + 4H2 → CH4 + 2H2O …(1)

[0006] Renewable energy is a pioneering example of utilizing CN utilities within the existing grid for distribution. For example, Non-Patent Document 1 describes a system in which the environmental value of electricity generated from renewable energy sources such as wind, solar, and hydropower, which do not emit CO2 during power generation, is added value in the form of non-fossil fuel certificates and traded.

[0007] In May 2018, a non-fossil fuel value trading market was established, allowing for the trading of certificates representing the non-fossil fuel value of electricity. A system for trading the value of CN (carbon dioxide) as a business is already being put in place in electricity trading. However, while the system is in place, there is still room for technological development to ensure transparency and fairness in transactions. For example, Patent Document 1 proposes a blockchain-based transaction management system for non-fossil fuel certificates. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-119143 [Non-patent literature]

[0009] [Non-Patent Document 1] Shin-Denryoku Net, “Non-Fossil Fuel Certificate”, [online], Shin-Denryoku Net, [Searched November 8, 2022], Internet,<URL:https: / / pps-net.org / glossary / 73482> [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The plan to introduce CN-CH4 into existing grids, as outlined in the aforementioned green growth strategy, applies the mechanism of non-fossil fuel certificates for electricity, but the treatment of electricity and gas differs significantly. With electricity, consumers can use electricity of the same quality regardless of whether it originates from fossil fuels or non-fossil fuels, but in the case of gas, the quality of gas used by consumers differs depending on the amount of CN-CH4 supplied to the grid.

[0011] The reason for this is that while the calorific value of city gas grade 13A, which is commonly distributed in many parts of Japan, is specified as 42-45 MJ / Nm3, the calorific value of methane is approximately 40 MJ / Nm3. Therefore, the quality of the gas distributed, i.e., the calorific value, changes depending on the amount of CN-CH4 injected into the grid. Consequently, in the case of CN-CH4, not only is it possible to trade certificates digitally, but physical operation and management of the grid are also necessary in addition to digital transactions.

[0012] To distribute CN-CH4 through existing gas grids and to realize fair trading of environmental value between CN-CH4 suppliers and users, it is necessary to consider that the calorific value of the gas in the grid will differ due to the supply of CN-CH4. The present invention aims to provide a carbon-neutral methane management system that manages the grid in response to changes in the gas composition within the gas grid and issues CN certificates. [Means for solving the problem]

[0013] To solve the aforementioned problems, the present invention Carbon neutral methaneThe management system is a carbon neutral methane management system used in a grid that supplies users with a mixed gas containing city gas supplied by a city gas supplier and carbon neutral methane supplied by a carbon neutral methane supplier, comprising: a calculation processing unit that calculates the calorific value of the mixed gas in the grid over a predetermined unit period; and a calculation processing unit that ensures the calorific value of the mixed gas in the grid calculated by the calculation processing unit falls within the constraints of the grid, by determining the amount of city gas supplied to the grid, the amount of city gas used by the users, and the amount of carbon neutral methane supplied to the grid over the predetermined unit period. A supply and utilization management unit that issues instructions to adjust at least one of the amount of larmethane supplied and the amount of carbon neutral methane used by the user; and a certificate issuing unit that issues a certificate certifying that the amount of carbon neutral methane supplied to the grid by the supplier of carbon neutral methane during a predetermined unit period is the amount of carbon neutral methane supplied after adjustment by the supply and utilization management unit, or a certificate certifying that the amount of carbon neutral methane used by the user during a predetermined unit period is the amount of carbon neutral methane used after adjustment by the supply and utilization management unit. A monitoring unit that acquires gas information within the grid, including the calorific value of the mixed gas within the grid, and constraint information for the grid, Equipped with The calculation processing unit updates the gas information in the grid for the predetermined unit period using at least one of the planned amount of carbon neutral methane supplied to the grid by the carbon neutral methane supplier and the planned amount of carbon neutral methane used by the user, and the gas information in the grid for the unit period prior to the predetermined unit period acquired by the monitoring unit. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a carbon-neutral methane management system that manages the grid in response to changes in the gas composition within the gas grid and issues CN certificates. [Brief explanation of the drawing]

[0015] [Figure 1] This is an overall configuration diagram showing the stakeholders and system configuration related to this embodiment. [Figure 2] This is an illustrative diagram explaining the process for issuing a CN-CH4 certificate. [Figure 3A] This is a diagram illustrating the process from application to adjustment for a CN-CH4 supply plan. [Figure 3B]It is a process image diagram from the application to the adjustment of the CN-CH4 utilization plan. [Figure 4A] It is a diagram explaining the CN-CH4 utilization application in period N. [Figure 4B] It is a diagram explaining the CN-CH4 supply application in period N + 1. [Figure 5] It is a diagram showing an example of trading CN-CH4 certificates in the CN-CH4 management system of each grid. [Figure 6] It is a diagram showing an example of trading CN-CH4 certificates in the CN-CH4 management system of each grid via an aggregation coordinator. [Figure 7] It is a diagram showing the CN-CH4 supply plan and the supply volume during the execution period, and the CN-CH4 utilization plan in period N.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the case of the same configuration, the same reference numerals will be given, and when the description overlaps, the description may be omitted. Also, the present invention is not limited to only realizing the following embodiments.

Examples

[0017] FIG. 1 is an overall configuration diagram showing the stakeholders and system configuration related to this embodiment. Thus, first, the overall concept of this embodiment will be described.

[0018] In the operation of an existing urban gas grid, an urban gas supplier 2 in each region supplies urban gas to a gas conduit, and an urban gas user 4 uses the urban gas supplied through the gas conduit as a heat source or the like. The urban gas supplier 2 mentioned here refers to, for example, a general gas conduit operator. This operator generally stores imported LNG from overseas in a tank at an LNG receiving base, and then vaporizes it, adjusts the calorific value, and adds odor treatment before supplying it to the gas conduit. Alternatively, natural gas mined in a domestic natural gas field is similarly adjusted in calorific value and odorized before being supplied to the gas conduit.

[0019] CN-CH4 supplier 3 is a business that supplies manufactured CN-CH4 to gas pipelines managed by the city gas suppliers 2 in each region, and in this embodiment, it is one or more such businesses. The CN-CH4 supplied to gas pipelines is a synthetic methane produced from CO2 emitted from sources such as biomass power plants, thermal power plants, and large-scale industrial facilities, and H2 produced using renewable energy sources such as solar, wind, and hydroelectric power, for example, through the electrolysis of water.

[0020] However, the combination of CO2 and H2 is not uniquely determined; any combination of CO2 that would have been released into the atmosphere if not reused and H2 produced using a method that does not release CO2 into the atmosphere during the manufacturing process is acceptable. Furthermore, the CN-CH4 supplier and the CN-CH4 manufacturer do not need to be the same person; in this embodiment, the CN-CH4 supplier 3 can be any business that ultimately supplies CN-CH4 to existing gas pipelines.

[0021] CN-CH4 users 5 are those who use CN-CH4 as fuel, etc. For example, this refers to businesses and / or end-users such as general households that wish to actively use CN-CH4 while using existing gas grids. For example, industrial businesses that are required to make a commitment to CN from the perspective of Scope 2 (indirect emissions from the use of electricity, heat, and steam supplied by other companies) are encouraged to actively use CN-CH4 from the perspective of decarbonizing their own utilities.

[0022] The CN-CH4 supply / utilization management system 1 shown in Figure 1 facilitates the smooth supply and utilization of CN-CH4 among the aforementioned stakeholders via a grid constructed from gas pipelines for city gas and a mixed gas including CN-CH4. For this purpose, the CN-CH4 supply / utilization management system 1 consists of a calculation processing unit 13, a grid status monitoring unit 14, a CN-CH4 supply / utilization management unit 12, and a certificate issuance unit 11.

[0023] The grid status monitoring unit 14 acquires and stores gas information and grid constraint information within the grid. The gas information within the grid includes information on the calorific value of the mixed gas within the grid. It may also include information on the gas state, such as the pressure of the gas within the grid. Furthermore, it is preferable that the grid status monitoring unit 14 can acquire gas information and constraint information from other grids.

[0024] The calculation processing unit 13 calculates the average calorific value of the mixed gas in the grid over a certain unit period. Specifically, the calculation processing unit 13 obtains the amount of city gas supplied to the grid, the amount of CN-CH4 supplied to the grid, the planned amount of CN-CH4 used by CN-CH4 users 5, and the gas information in the grid at the start of that unit period obtained by the grid status monitoring unit 14, and from this information calculates the amount of gas calorific value that will be used for issuing certificates during the period in which CN-CH4 is traded.

[0025] The CN-CH4 supply / utilization management unit 12 is responsible for adjusting the amount of heat generated within the gas grid, taking into account status information such as the calorific value and pressure of the gas within its own grid, as well as information on the surplus or shortage of CN-CH4 in other grids, and calorific value limits for the gas within the grid, such as the lower limit setting of the gas calorific value determined by the equipment specifications of end users, and the upper limit of CN-CH4 supply determined by laws and regulations.

[0026] The CN-CH4 supply / utilization management unit 12 issues commands to adjust at least one of the following: the amount of city gas supplied to the grid, the amount of city gas used by users from the grid, the amount of CN-CH4 supplied to the grid, and the amount of CN-CH4 used by users, so that the calorific value of the mixed gas in the grid, calculated by the calculation processing unit, falls within the grid constraints. The CN-CH4 supply / utilization management unit 12 transmits the final adjusted CN-CH4 supply and CN-CH4 usage amounts as a supply and utilization plan to the calculation processing unit 13. The calculation processing unit 13 transmits the gas information in the grid for the next period to the CN-CH4 supply / utilization management unit 12, along with the gas information in the grid acquired from the grid status monitoring unit 14 at that time.

[0027] The certificate issuing unit 11 receives the final version of the CN-CH4 supply and utilization plan and gas information such as the calorific value within the grid for the next period from the CN-CH4 supply / utilization management unit 12. Based on this information, it issues a CN-CH4 certificate to the CN-CH4 supplier 3 authorizing the supply of a predetermined amount of CN-CH4 within the relevant period, and a CN-CH4 certificate to the CN-CH4 user 5 authorizing the use of a predetermined amount of CN-CH4 within the relevant period.

[0028] Although not shown in the diagram, in order to manage whether the CN-CH4 supply and utilization plans for which CN-CH4 certificates have been issued are actually being implemented, measuring instruments such as flow meters are installed at the outlet of the CN-CH4 supplier and the inlet of the CN-CH4 user. The CN-CH4 supply / utilization management department acquires this information and manages the status of plan implementation.

[0029] The CN-CH4 supply / utilization management system 1 comprises a processor, a communication interface, a storage device, and an input / output interface. The CN-CH4 supply / utilization management system 1 may consist of a single server or other computer, or multiple servers or other computers may work together to provide various functions.

[0030] The processor is a central processing unit that controls the operation of each part of the CN-CH4 supply / utilization management system 1. The processor can be, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an ASIC (Application Specific Integrated Circuit). The memory device stores programs executed by the processor, data processed by the processor, etc. The memory device can be flash memory, RAM (Random Access Memory), ROM (Read Only Memory), etc. The communication interface is an interface for communicating with the outside world via a network such as the Internet. The input / output interface receives operation instructions from an administrator who operates input devices connected to the input / output interface. Input devices can be, for example, a keyboard, touch panel, mouse, microphone, etc. Furthermore, display devices such as LCDs, EL (Electroluminescence) panels, and organic EL panels, as well as output devices such as printers and speakers, can be connected to the input / output interface. The input / output interface outputs data and information processed by the processor, and data and information stored in the main memory, to the output devices. The communication interface enables communication between the CN-CH4 management system and city gas suppliers, CN-CH4 suppliers, CN-CH4 users, CN-CH4 supply / utilization management systems that manage other grids, aggregation coordinators, and others. [Examples]

[0031] In Examples 2 and below, the same configuration as in Example 1 will not be described. In this embodiment, an example in which the CN-CH4 supply / utilization management unit 12 in the CN-CH4 supply / utilization management system 1 shown in Figure 1 adjusts the CN-CH4 supply and utilization plan, and certifies that the CN-CH4 supplier 3 and CN-CH4 user 5 will supply and utilize CN-CH4, is explained with reference to Figures 2, 3A, and 3B. Figure 2 is an illustrative diagram illustrating the flow up to the issuance of a CN-CH4 certificate, and Figures A and 3B are illustrative diagrams showing an example of a CN-CH4 supply and utilization plan adjustment method.

[0032] First, Figure 2 illustrates the plan and execution schedule for issuing CN-CH4 certificates. In order for CN-CH4 supplier 3 to actually supply CN-CH4 to the gas grid and CN-CH4 user 5 to utilize it, a planning period is required for applying for and adjusting the CN-CH4 supply and utilization plans, as shown in Figure 2, and an execution period is required to carry out the decided CN-CH4 supply and utilization plans.

[0033] In period N shown in Figure 2, the CN-CH4 supply and utilization plans are adjusted during planning period N, while the CN-CH4 supply and utilization plans approved in the previous period N-1 (not shown) are implemented as implementation period N-1.

[0034] There are no limitations on the length of periods N, N+1, or N+2. However, setting a long period may reduce the accuracy of the CN-CH4 supply and utilization plans. Therefore, it is preferable to set a period that does not reduce the prediction accuracy of the plans, for example, about one month.

[0035] The planning period mainly includes the CN-CH4 supply plan application period (supply plan application in Figure 2), the CN-CH4 supply plan adjustment period (supply plan adjustment in Figure 2), the CN-CH4 utilization plan application period (utilization plan application in Figure 2), the CN-CH4 utilization plan adjustment period (utilization plan adjustment in Figure 2), the grid gas information update and CN-CH4 certificate issuance period.

[0036] Of these, the CN-CH4 supply plan application period, CN-CH4 supply plan adjustment period, CN-CH4 utilization plan application period, and CN-CH4 utilization plan adjustment period may be in any order other than that shown in Figure 2, and may overlap or be rearranged; there are no limitations. However, if the CN-CH4 utilization plan application is started after the CN-CH4 supply plan adjustment, there will be no need to readjust the CN-CH4 utilization plan, so it is preferable to follow the order shown in Figure 2.

[0037] During the grid gas information update and CN-CH4 certificate issuance period, the calculation processing unit 13 shown in Figure 1 first updates the grid gas information for the next period based on the CN-CH4 and city gas supply plans obtained from the CN-CH4 supplier 3 and city gas supplier 2, and the grid gas information obtained from the grid status monitoring unit 14.

[0038] This grid gas information includes, for example, calorific value. Currently, when users utilize city gas, the charge is calculated based on the volume used. However, when CN-CH4 is mixed into the grid, its calorific value is lower than that of city gas, thus reducing the grid's overall calorific value. Therefore, when calculating the charge based on the volume used, the volume used increases under the same calorific value, resulting in a higher cost burden for consumers.

[0039] Therefore, it is necessary to understand the calorific value of the gas within the grid during the implementation period and to determine the amount of CN-CH4 used and its charges based on calorific value. To achieve this, it is necessary to calculate and update the gas information within the grid, especially the calorific value of the gas within the grid. Furthermore, CN-CH4 may not be supplied and utilized as planned during the actual implementation period. Therefore, grid gas information will be updated to reflect both the CN-CH4 supply and utilization plans and the actual supply and utilization status during the implementation period.

[0040] The timing for updating the gas information within this grid may be at any time, but it is particularly preferable to do so after the adjustment of the CN-CH4 supply plan and utilization plan has been completed. In this embodiment, the update is performed at the end of the planning period after the adjustment of the CN-CH4 utilization plan has been completed.

[0041] After the update of the gas information within this grid is complete, a CN-CH4 certificate will be issued that includes the calorific value of the supplied gas in the CN-CH4 supply plan and the calorific value of the used gas in the utilization plan. At this time, the calorific value of the supplied gas in the CN-CH4 supply plan and the calorific value of the used gas in the utilization plan will be obtained from the updated gas information within the grid, taking into account the CN-CH4 supply plan and utilization plan.

[0042] In this embodiment, the CN-CH4 supply and utilization plans for which CN-CH4 certificates were issued during period N in Figure 2 are actually supplied and utilized during the execution period N+1. Simultaneously with this execution, the next CN-CH4 supply and utilization plans are adjusted, and CN-CH4 certificates are issued. Thereafter, the planning and execution are repeated in this order.

[0043] The above outlines the process for issuing the CN-CH4 certificate shown in Figure 2. From here on, Figures 3A and 3B will be used to explain how to adjust the CN-CH4 supply and utilization plans necessary for issuing the CN-CH4 certificate.

[0044] Figure 3A is a diagram illustrating the processing steps from application to adjustment for a CN-CH4 supply plan, and Figure 3B is a diagram illustrating the processing steps from application to adjustment for a CN-CH4 utilization plan. Hatching indicates the amount of city gas, and white areas indicate the amount of CN-CH4. In this embodiment, the adjustments in Figures 3A and 3B are explained assuming that the items for the planning period (CN-CH4 supply plan application / adjustment, CN-CH4 utilization plan application / adjustment) are arranged in order as shown in Figure 2, but the embodiment is not limited to this.

[0045] First, Figure 3A will explain the CN-CH4 supply plan. In a situation where only city gas is available, as in the past, when CN-CH4 supplier 3 supplies CN-CH4 to the gas grid, CN-CH4 supplier 3 applies to the CN-CH4 supply / utilization management system 1 for a CN-CH4 supply plan. Depending on the amount requested in the supply plan, it may fall within the grid's constraints (CN-CH4 supply plan application a) or it may not fall within the grid's constraints (CN-CH4 supply plan application b). The grid constraints in this case include, but are not limited to, grid pressure and the upper limit of CN-CH4 supply.

[0046] In the case of CN-CH4 supply plan application a, the CN-CH4 supply plan will be approved for all CN-CH4 suppliers 3 and the process will move to a CN-CH4 utilization plan. However, in the case of CN-CH4 supply plan application b, adjustments to the supply plan will be necessary. Possible methods of adjustment include reducing the CN-CH4 supply plan (CN-CH4 supply plan adjustment b1), reducing the amount of city gas supplied (CN-CH4 supply plan adjustment b2), or reducing both the amount of city gas and CN-CH4 supplied.

[0047] For example, when reducing the planned supply amount of CN-CH4, as in CN-CH4 supply plan adjustment b1, the reduction in the planned supply amount may be instructed to each CN-CH4 supplier 3 in an equal proportion, or the planned supply amount may be reduced by a first-come, first-served basis for supply plan applications, a lottery, etc., and there are no limitations. Similarly, when reducing the amount of city gas supplied, as in CN-CH4 supply plan adjustment b2, if there are multiple city gas suppliers 2, the reduction in the supply amount should be instructed in the manner described above. As described above, the CN-CH4 supply plan has been adjusted and approved.

[0048] Next, Figure 3B will explain the application for a CN-CH4 utilization plan. Figure 3B shows the case where the CN-CH4 supply plan for CN-CH4 supply plan adjustment b2 is approved, and then the application transitions to a CN-CH4 utilization plan.

[0049] CN-CH4 user 5 applies to the CN-CH4 supply / utilization management system 1 for a planned amount of CN-CH4 usage. In this case, the total amount of requested usage may be less than or equal to the planned supply amount of CN-CH4 (CN-CH4 usage plan application c), or it may be greater than the planned supply amount of CN-CH4 (CN-CH4 usage plan application d). In the case of CN-CH4 usage plan application c, the CN-CH4 usage plan is approved for all CN-CH4 users 5. However, in the case of CN-CH4 usage plan application d, the planned amount of usage needs to be reduced, and the CN-CH4 supply / utilization management unit 12 makes the necessary adjustments.

[0050] The adjustment method is the same as the method used to adjust the CN-CH4 supply plan; it may involve instructing each CN-CH4 user 5 to reduce their planned usage amount in an equal proportion, reducing the planned usage amount by means of a first-come, first-served basis for application, a lottery, or adjusting the sales cost of CN-CH4 to reduce demand; however, it is not limited to these methods. As described above, the CN-CH4 supply / usage management department 12 adjusts and approves the CN-CH4 usage plan.

[0051] After the CN-CH4 supply / utilization management unit 12 approves the CN-CH4 supply plan and utilization plan, the CN-CH4 supply / utilization management unit 12 transmits the CN-CH4 supply plan and city gas supply plan information to the calculation processing unit 13. The calculation processing unit 13 then updates the gas information in the grid for the next period in which the plan will be implemented, based on the supply plan information and the gas information in the grid obtained from the grid status monitoring unit 14.

[0052] Here, when the calculation processing unit 13 calculates the calorific value of the gas information within the grid, if the planned supply amount of CN-CH4 is X vol% of the total grid gas amount within the grid, the average calorific value of the entire next period N+1, Have,N+1, is calculated using the following equation (2). Here, H is the calorific value [MJ / Nm3], and Have,N, Have,N+1, and HCH4 represent the average calorific value of the current period N, the average calorific value of the next period N+1, and the calorific value of methane, respectively. Have,N+1 = HCH4 × X / 100 + Have,N × (1-X / 100) …(2)

[0053] After approval of the CN-CH4 supply and utilization plans and calculation of the grid gas information for the next period, the CN-CH4 supply / utilization management unit 12, as described in Example 1, adjusts the CN-CH4 supply / utilization plan and the grid gas calorific value information calculated by the calculation processing unit 13, and issues a CN-CH4 certificate to the CN-CH4 supplier 3, authorizing them to supply a predetermined amount of CN-CH4 within the relevant period, and a CN-CH4 certificate to the CN-CH4 user 5, authorizing them to utilize a predetermined amount of CN-CH4 within the relevant period.

[0054] Next, an example of a CN-CH4 certificate in this embodiment will be described. If the calorific value of methane HCH4 is 40.00 MJ / Nm3, the calorific value of gas in the grid during the current period (Have,N) is 43.00 MJ / Nm3, and the volume fraction X of the planned supply of CN-CH4 in the next period relative to the amount of gas in the grid is 1 vol%, then the average calorific value of gas in the grid during the next period (Have,N+1) will be 42.97 MJ / Nm3 from equation (2).

[0055] When CN-CH4 user 5 applies for the use of 1000 MJ of CN-CH4 and this is approved by the CN-CH4 supply / use management system 1, CN-CH4 user 5 will be able to use 23.3 Nm3 of the grid's gas as CN-CH4. It is preferable that the CN-CH4 certificate includes these types of values. Furthermore, CN-CH4 user 5 will be counted as having emitted CO2 for any gas used in excess of 23.3 Nm3.

[0056] According to this embodiment, it is possible to adjust the CN-CH4 supply plan and utilization plan, and at the same time issue CN-CH4 certificates according to the actual gas conditions in the grid, i.e., the CN-CH4 mixing rate. [Examples]

[0057] In this embodiment, a method for dealing with a situation where the planned amount of CN-CH4 utilization is less than the planned amount of CN-CH4 supply, resulting in CN-CH4 physically remaining in the grid for the next period, is explained with reference to Figures 4A, 4B, 5, and 6.

[0058] Figure 4A illustrates the application for CN-CH4 use during period N, showing a situation where the planned amount of CN-CH4 use is less than the planned amount of CN-CH4 supply adjusted and approved by the CN-CH4 supply / use management unit 12 during the planned period N. This means that if the supply and use of CN-CH4 are carried out as planned during the execution period, there will be a surplus of CN-CH4 in the grid. At this time, as explained in Example 2, all the plans applied for by CN-CH4 users 5 are approved, and CN-CH4 certificates are issued.

[0059] Thus, if it is known during the planning stage of period N that CN-CH4 will definitely remain on the grid when period N+1 is executed, it is preferable to plan the CN-CH4 supply in period N+1 taking that remaining CN-CH4 into consideration, as shown in Figure 4B, which illustrates the CN-CH4 supply application in period N+1.

[0060] In detail, if the total amount of CN-CH4 supplied by CN-CH4 supplier 3 in their supply plan is still within the grid constraint range even after taking into account the remaining amount of CN-CH4 (CN-CH4 supply plan application a), then all of CN-CH4 supplier 3's supply plans will be approved. However, if the total amount of CN-CH4 supplied by CN-CH4 supplier 3 in their supply plan already exceeds the grid constraint range (CN-CH4 supply plan application b), or if it does not fall within the grid constraint range even after taking into account the remaining amount of CN-CH4 (not shown), then the CN-CH4 supply plan adjustment method described in Example 2 will be used for adjustment.

[0061] In this case, if the supply of CN-CH4 significantly exceeds the grid constraints, the CN-CH4 supply / utilization management unit 12 adjusts the supply amount of CN-CH4 or city gas. However, in order to aim for carbon neutrality, an adjustment method that reduces the supply amount of city gas (CN-CH4 supply plan adjustment b2) is preferred.

[0062] The above explains the adjustment of the supply plan for any remaining CN-CH4. While this remaining CN-CH4 can be traded in the next period's CN-CH4 utilization plan, it may remain again, and there is a possibility that the amount of remaining CN-CH4 will increase in the long term. In that case, as a physical problem, the fraction of CN-CH4 in the grid will increase, falling below the design calorific value of existing grid gas-using equipment.

[0063] To address this, a threshold may be set for the calorific value of the current period's in-grid gas information acquired by the grid status monitoring unit 14 and the next period's in-grid information updated by the calculation processing unit 13. If the calorific value falls below the threshold, a high-calorific value gas such as propane or butane may be supplied to the grid to adjust the calorific value.

[0064] Furthermore, regarding the remaining CN-CH4s that increase under the above circumstances, it is also possible to transfer or sell the CN-CH4 certificates to other grids that are not connected. In more detail, the CN-CH4 supply / utilization management unit 12 transmits the remaining amount of CN-CH4 shown in Figure 4A to the certificate issuance unit 11, and the certificate issuance unit 11 issues a CN-CH4 certificate.

[0065] As shown in Figure 5, the issued CN-CH4 certificates may be directly traded, transferred, or sold by each grid's CN-CH4 supply / utilization management system 1, or, as shown in Figure 6, an aggregation coordinator may be established to consolidate the transactions of CN-CH4 certificates. The method of transactions with other grids is not limited.

[0066] If the remaining CN-CH4 is traded with other grids as CN-CH4 certificates, the CN-CH4 remaining in the grid will no longer be carbon neutral. Therefore, the CN-CH4 supply / utilization management unit 12 manages this information, incorporates it into the grid gas information for the next period, and adjusts the CN-CH4 utilization plan when planning CN-CH4 utilization, taking into account that it is not subject to CN-CH4 application.

[0067] According to this embodiment, in situations where the amount of CN-CH4 used is less than the planned supply amount of CN-CH4, resulting in CN-CH4 physically remaining in the grid during the next period, it becomes possible to adjust the CN-CH4 supply plan, respond when the specifications of grid gas-using equipment cannot be met due to fluctuations in the amount of heat generated within the grid, and operate digitally for trading CN-CH4 certificates.

[0068] Furthermore, although this embodiment describes a situation where the planned amount of CN-CH4 utilization is less than the planned amount of CN-CH4 supply, the above method can similarly address the case where the amount of CN-CH4 used by CN-CH4 user 5 during the execution period is less than the planned amount of CN-CH4 utilization. [Examples]

[0069] Next, we will explain how to handle a situation in the CN-CH4 supply / utilization management system 1 of the embodiment where, during the execution period, a CN-CH4 supplier 3 is unable to supply CN-CH4 according to the approved supply plan, even though the plan was approved and a CN-CH4 certificate was issued during the planning period, due to equipment failure or other problems. In this case, the actual amount of CN-CH4 supplied will be less than the supply plan, and the gas information within the grid, such as the actual calorific value, will change as recorded in the CN-CH4 certificate.

[0070] Figure 7 shows the CN-CH4 supply plan and supply volume during the implementation period, as well as the CN-CH4 utilization plan, for period N. Figure 7 also shows that there are three CN-CH4 suppliers, A, B, and C, each with a CN-CH4 supply plan approved by a CN-CH4 certificate. However, it illustrates a situation where the supply volume of supplier A falls below the CN-CH4 supply plan volume for which the CN-CH4 certificate was issued during the implementation period shown in CN-CH4 supply (implementation).

[0071] In this case, as mentioned above, the inability to supply CN-CH4 reduces the proportion of CN-CH4 in the grid, leading to an increase in heat generation within the grid, which differs from the heat generation stated on the CN-CH4 certificate.

[0072] In other words, CN-CH4 certificates are issued on a calorific value basis, and CN-CH4 users (5) convert this to usable volume according to the actual measurement equipment. Therefore, if the gas with increased calorific value is used in the volume stated on the CN-CH4 certificate, it will be considered that more calorific value has been used than that stated on the CN-CH4 certificate. In this case, if the gas seller sells the gas at the price per unit of calorific value, their revenue will decrease.

[0073] As a countermeasure against the reduction in revenue for gas retailers caused by these fluctuations in calorific value, CN-CH4 supplier 3 A may bear the cost, or CN-CH4 supplier 3 may pay a fixed monthly amount to CN-CH4 supply / utilization management system 1 as insurance for such situations, and CN-CH4 supply / utilization management system 1 may bear the cost; however, the method is not limited to this.

[0074] Equation (3) shows an example of a formula for calculating the amount Y[\] borne by CN-CH4 supplier A, if A bears the cost. Y = {(Have,Actu - Have,Plan) / Have,Plan} ×Z·W [\]…(3)

[0075] Here, Have is the average calorific value [MJ / Nm3], Z is the total CN-CH4 calorific value supplied for one period determined in the CN-CH4 supply plan [MJ], and W is the gas sales price [\ / MJ]. The subscripts Plan and Actu refer to the planning and execution times, respectively. The average calorific values ​​Have and Plan within the grid during the planning time are calculated in the calculation processing unit 13 using equation (2), and the average calorific values ​​Have and Actu during execution are obtained from the grid status monitoring unit 14.

[0076] Furthermore, if the amount of CN-CH4 supplied by CN-CH4 supplier A falls below the planned supply amount, the total amount of CN-CH4 supplied will decrease. However, there are cases where the amount is still greater than the planned CN-CH4 utilization amount (CN-CH4 utilization plan c), and cases where it falls below the planned CN-CH4 utilization amount (CN-CH4 utilization plan d).

[0077] In the case of the latter CN-CH4 utilization plan d, the deficit must be covered by purchasing CN-CH4 certificates from other grids, as explained in Figure 5 or Figure 6, or by paying CO2 emission costs for the CO2 emissions resulting from the deficit. In this situation, the burden may be placed on CN-CH4 supplier 3 A, or the burden may be placed on CN-CH4 supply / utilization management system 1 by paying a fixed amount to CN-CH4 supply / utilization management system 1 every month. [Explanation of Symbols]

[0078] 1. CN-CH4 Supply / Utilization Management System (Carbon Neutral Methane Management System) 11. Certificate Issuance Department 12 CN-CH4 Supply / Usage Management Department (Supply and Utilization Management Department) 13. Arithmetic Processing Unit 14 Grid Status Monitoring Unit 2. City gas suppliers 3 CN-CH4 Supplier 4. City gas users 5 CN-CH4 users

Claims

1. A carbon-neutral methane management system used in a grid that supplies users with a mixed gas containing city gas supplied by a city gas supplier and carbon-neutral methane supplied by a carbon-neutral methane supplier, A calculation processing unit that calculates the calorific value of the mixed gas in the grid during a predetermined unit period, A supply and utilization management unit gives instructions to adjust at least one of the following during a predetermined unit period: the amount of city gas supplied to the grid, the amount of city gas used by the user, the amount of carbon neutral methane supplied to the grid, and the amount of carbon neutral methane used by the user, so that the calorific value of the mixed gas in the grid calculated by the calculation processing unit falls within the constraints of the grid. A certificate issuing unit that issues a certificate certifying that the amount of carbon neutral methane supplied to the grid by the carbon neutral methane supplier during the predetermined unit period is the amount of carbon neutral methane supplied after adjustment by the supply and utilization management unit, or a certificate certifying that the amount of carbon neutral methane used by the user during the predetermined unit period is the amount of carbon neutral methane used after adjustment by the supply and utilization management unit, A monitoring unit that acquires gas information within the grid, including the calorific value of the mixed gas within the grid, and constraint information for the grid, Equipped with, The calculation processing unit updates the gas information in the grid for the predetermined unit period using at least one of the planned amount of carbon neutral methane supplied to the grid by the carbon neutral methane supplier and the planned amount of carbon neutral methane used by the user during the predetermined unit period, and the gas information in the grid for the unit period prior to the predetermined unit period acquired by the monitoring unit. A carbon-neutral methane management system characterized by the following:

2. In the carbon-neutral methane management system according to claim 1, The aforementioned supply and utilization management unit, If the gas information within the grid for the predetermined unit period updated by the calculation processing unit is outside the range of the grid constraint, the planned supply amount of city gas to the grid or the planned supply amount of carbon neutral methane to the grid for the predetermined unit period is changed to adjust the gas information within the grid for the predetermined unit period so that it falls within the grid constraint. The city gas supplier or the carbon neutral methane supplier is instructed to change the planned supply amount. A carbon-neutral methane management system characterized by the following:

3. In the carbon-neutral methane management system according to claim 1, The aforementioned supply and utilization management unit, In the predetermined unit period, if the planned amount of carbon neutral methane used by the user is greater than the planned amount of carbon neutral methane supplied to the grid by the carbon neutral methane supplier, the planned amount of use shall be modified so as not to exceed the planned supply amount. The user is instructed on the revised planned amount of carbon-neutral methane to be used. A carbon-neutral methane management system characterized by the following:

4. In the carbon-neutral methane management system according to claim 1, The supply and utilization management unit transmits information about the excess amount of carbon neutral methane to the certificate issuing unit when the amount of carbon neutral methane planned for use by the user is less than the amount of carbon neutral methane planned for supply to the grid by the carbon neutral methane supplier. The certificate issuing unit issues information on the surplus amount of carbon-neutral methane as a carbon-neutral methane certificate. The Supply and Utilization Management Unit transfers the carbon neutral methane certificate to another grid. A carbon-neutral methane management system characterized by the following:

5. In the carbon-neutral methane management system according to claim 1, The aforementioned supply and utilization management unit, If the amount of carbon-neutral methane planned for use by the user exceeds the amount of carbon-neutral methane planned for supply to the grid by the carbon-neutral methane supplier, the amount of carbon-neutral methane that is insufficient will be adjusted by obtaining a carbon-neutral methane certificate that shows information on the surplus amount of carbon-neutral methane in other grids and adjusting the planned use amount and the planned supply amount. A carbon-neutral methane management system characterized by the following:

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