Modularized rail transit carbon emission accounting method

Abstract

The invention relates to the technical field of rail transit carbon emission accounting, in particular to a modular rail transit carbon emission accounting method, which comprises the steps of S1, acquiring a rail transit carbon emission accounting project; s2, extracting a plurality of accounting main body modules; s3, extracting a plurality of accounting stage modules at the lower layer of each accounting main body module; s4, extracting a plurality of accounting range modules on the lower layer of each accounting stage module; s5, obtaining a plurality of accounting subentry project minimum modules based on each accounting main body module, each accounting stage module and each accounting range module; s6, performing carbon emission calculation and uncertainty analysis on the minimum module of each accounting subentry project to obtain a carbon emission accounting result and an uncertainty grade; and S7, generating a corresponding carbon emission characteristic analysis result based on the carbon emission accounting result and the uncertainty grade of the minimum module of each accounting item project. According to the invention, the accuracy and flexibility of rail transit carbon emission accounting can be improved.

Description

Technical Field

[0001] This invention relates to the field of carbon emission accounting technology for rail transit, and specifically to a modular carbon emission accounting method for rail transit. Background Technology

[0002] With the increasingly severe environmental problems caused by global climate change, carbon emission control has become a critical issue that urgently needs to be addressed. Transportation, as one of the three major sources of carbon emissions, continues to see a steady increase in its carbon emissions. Currently, clear directions and quantifiable targets have been proposed for the low-carbon development of rail transit.

[0003] As a crucial component of transportation, rail transit is experiencing rapid development. With the continuous expansion of its rail network and the sustained growth of passenger flow, its total energy consumption cannot be ignored. However, currently, there is no unified accounting system for carbon emissions from rail transit, and significant regional differences still exist.

[0004] In order to truly leverage its green and low-carbon advantages and effectively support the industry's own carbon emission reduction path planning and target achievement, it is urgent to establish a scientific, unified, and accurate carbon emission accounting system for rail transit, clearly understand the current status and changing trends of its carbon footprint throughout its entire life cycle, and construct a comprehensive carbon emission accounting system for rail transit is of great practical significance.

[0005] A carbon emission accounting system for rail transit is the foundation and prerequisite for achieving precise carbon management in the industry. The applicant found that only through scientific and standardized accounting methods can the actual carbon emission levels under different lines, operating modes, and technological applications be accurately quantified, emission hotspots (such as high-energy-consuming stations and train traction systems) be identified, and data support be provided for formulating targeted emission reduction measures to avoid blind emission reduction actions.

[0006] Therefore, designing a carbon emission accounting method for rail transit that balances accuracy and flexibility is an urgent technical problem that needs to be solved. Summary of the Invention

[0007] To address the shortcomings of the existing technologies, the technical problem this invention aims to solve is: how to provide a modular method for calculating carbon emissions from rail transit. By constructing a multi-level, multi-dimensional modular system consisting of "the main calculation module, the calculation stage module, the calculation scope module, and the minimum module of the calculation sub-project (i.e., the carbon emission source module of the calculation sub-project)," this method provides a quantitative basis for high-risk decisions such as carbon trading, carbon neutrality commitments, and low-carbon technology investment, thereby improving the accuracy and flexibility of carbon emission calculation for rail transit.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A modular method for carbon emission accounting in rail transit includes:

[0010] S1: Obtain pending rail transit carbon emission accounting projects;

[0011] S2: Based on the carbon emission accounting project for rail transit, extract several main accounting modules;

[0012] S3: Based on the carbon emission accounting project for rail transit, extract several accounting stage modules at the lower level of each accounting main module;

[0013] S4: Based on the carbon emission accounting project for rail transit, extract several accounting scope modules at the lower level of each accounting stage module;

[0014] S5: Based on the various accounting main modules, accounting stage modules, and accounting scope modules in the rail transit carbon emission accounting project, several minimum modules of accounting sub-projects are obtained;

[0015] S6: Perform carbon emission calculations and uncertainty analysis on the smallest modules of each accounting sub-project of the rail transit carbon emission accounting project to obtain the corresponding carbon emission accounting results and uncertainty levels;

[0016] S7: Based on the carbon emission accounting results and uncertainty levels of the smallest modules of each accounting sub-project in the rail transit carbon emission accounting project, generate corresponding carbon emission characteristic analysis results.

[0017] Preferably, in step S2, the main accounting module includes station A1, track line A2 and / or vehicle depot A3.

[0018] Preferably, in step S3, the accounting stage module includes the construction preparation stage B1, the construction stage B2, and / or the operation and management stage B3.

[0019] Preferably, in step S4, the accounting scope module includes direct carbon emissions C1-C3, indirect carbon emissions C4-C6, and other indirect carbon emissions C7-C9.

[0020] Preferably, in step S5, the minimum module for calculating the sub-item project includes:

[0021] 1) Direct carbon emissions of the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3; C1 is the smallest module of the unaccounted sub-project.

[0022] 2) Indirect carbon emissions of the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3; C4 is the smallest module of the unaccounted sub-project.

[0023] 3) The minimum module for the accounting of other indirect carbon emissions C7 in the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for building material production, vehicle construction, precast concrete construction, waterproof material production, rail production, safety protection material production, electrical equipment production, air conditioning system equipment production, lighting system equipment production, water supply and drainage equipment production, intelligent building equipment production and / or other related equipment production and corresponding material transportation;

[0024] 4) The minimum module for the accounting of direct carbon emissions C2 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for fuel of preliminary survey equipment, fuel of on-site transportation equipment, fuel of construction machinery, fuel of office and living area equipment, gas of temporary heating system, gas of welding operation and / or gas of small machinery.

[0025] 5) The minimum module for the accounting of indirect carbon emissions C5 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for electricity consumption of on-site machinery and equipment, electricity consumption of equipment trial operation, electricity consumption of office and living areas, heat consumption of production and processing equipment and / or heat consumption of office and living areas.

[0026] 6) The minimum module for the accounting of other indirect carbon emissions C8 during the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in office and living area and / or waste transportation and treatment during construction.

[0027] 7) The minimum module for the direct carbon emission accounting of the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting of heating system gas, domestic hot water system gas, cooking system gas, backup power fuel oil, emergency system fuel oil and / or maintenance equipment fuel oil.

[0028] 8) The minimum module for the accounting of indirect carbon emissions C6 in the operation and management phase B3 of station A1 / railway line A2 / vehicle depot A3 includes: electricity consumption for heating, air conditioning and ventilation systems, electricity consumption for lighting systems, electricity consumption for water supply and drainage systems, electricity consumption for elevator systems, electricity consumption for cooking systems, electricity consumption for indoor electrical equipment, electricity consumption for building intelligent monitoring systems, electricity consumption for train traction systems, electricity consumption for operating vehicles, electricity consumption for other special energy requirements, heat consumption for centralized heating systems, heat consumption for centralized domestic hot water systems and / or cooling consumption for centralized cooling systems;

[0029] 9) The minimum module for the accounting of other indirect carbon emissions C9 in the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in living and office area and / or greening maintenance.

[0030] Preferably, in step S6, the carbon emission calculation results and uncertainty level of the smallest module of the accounting sub-project are calculated through the following steps:

[0031] S601: Determine the carbon emission factors and activity data required for calculating the carbon emissions of the smallest module of the sub-project based on the carbon emission factor method;

[0032] S602: Calculate the carbon emissions of the smallest module of the sub-project based on carbon emission factors and activity data;

[0033] The formula is expressed as:

[0034] ;

[0035] In the formula: Indicates carbon emissions; Represents activity data; Indicates carbon emission factor;

[0036] S603: Determine the individual uncertainty level of carbon emission factors and activity data, and map the individual uncertainty level to the corresponding individual relative uncertainty.

[0037] S604: Calculate the relative combined standard uncertainty of the smallest module of the sub-project based on the individual relative uncertainty of carbon emission factors and activity data;

[0038] S605: Determine the uncertainty level of the smallest module of a sub-project based on the relative combined standard uncertainty assessment;

[0039] S606: Expand the relative combined standard uncertainty of the smallest module of the accounting sub-item project to obtain the relative expanded uncertainty;

[0040] S607: Calculate the corresponding accounting error based on the carbon emissions and relative expanded uncertainty of the smallest module of the accounting sub-project;

[0041] S608: Calculate the corresponding carbon emission accounting results based on the carbon emission of the smallest module of the accounting sub-project and the accounting error.

[0042] Wherein, carbon emission accounting result = carbon emission amount ± accounting error amount;

[0043] S609: Output the carbon emission calculation results and uncertainty level of the smallest module of the accounting sub-project.

[0044] Preferably, in step S604, the relative combined standard uncertainty is calculated using the following formula:

[0045] ;

[0046] In the formula: This represents the relative combined standard uncertainty; This represents the individual relative uncertainty of the activity data; This represents the individual relative uncertainty of the carbon emission factor.

[0047] Preferably, in step S606, the relative expanded uncertainty is calculated using the following formula:

[0048] ;

[0049] In the formula: This represents the relative expanded uncertainty; This represents the relative combined standard uncertainty; This represents the expansion factor.

[0050] Preferably, in step S607, the accounting error is calculated using the following formula:

[0051] ;

[0052] In the formula: Indicates the amount of accounting error; This represents the relative expanded uncertainty; This indicates carbon emissions.

[0053] Preferably, in step S6, after calculating the carbon emission accounting results and uncertainty levels of the smallest module of each accounting sub-item, the following calculations are performed:

[0054] 1) The carbon emission calculation results of all the smallest modules of the accounting sub-projects under the accounting scope module are summed to obtain the carbon emission calculation result of the accounting scope module. At the same time, the relative expanded uncertainty of all the smallest modules of the accounting sub-projects is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting scope module. The uncertainty level of the accounting scope module is determined based on the expanded uncertainty.

[0055] Among them, error propagation calculation refers to: summing up the squares of the relative expanded uncertainty of the smallest module of all accounting sub-items and then performing square root calculation;

[0056] 2) The carbon emission accounting results of all accounting scope modules under the accounting stage module are summed to obtain the carbon emission accounting result of the accounting stage module. At the same time, the expanded uncertainty of all accounting scope modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting stage module. The uncertainty level of the accounting stage module is determined based on the expanded uncertainty.

[0057] 3) The carbon emission accounting results of all accounting stage modules under the main accounting module are summed to obtain the carbon emission accounting result of the main accounting module. At the same time, the expanded uncertainty of all accounting stage modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the main accounting module. The uncertainty level of the main accounting module is determined based on the expanded uncertainty.

[0058] 4) The carbon emission accounting results of all accounting modules under the rail transit carbon emission accounting project are summed to obtain the carbon emission accounting result of the rail transit carbon emission accounting project. At the same time, the expanded uncertainty of all accounting modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the rail transit carbon emission accounting project. The uncertainty level of the rail transit carbon emission accounting project is determined based on the expanded uncertainty.

[0059] Compared with existing technologies, the modular rail transit carbon emission accounting method of this invention has the following advantages:

[0060] This invention achieves a refined, multi-dimensional analysis of the carbon footprint of rail transit throughout its entire lifecycle, solving the "black box" problem of traditional accounting. By constructing a three-dimensional modular system with the accounting subject (stations, lines, and vehicle depots) as the warp and the lifecycle stages (construction preparation stage, construction stage, and operation management stage) as the weft, and embedding three layers of emission source scope (direct emissions, indirect emissions, and other indirect carbon emissions), this invention systematically breaks down the complex total carbon emissions of rail transit into the smallest carbon emission source modules (i.e., the smallest modules of the accounting sub-projects). This allows rail transit carbon emission accounting projects to calculate carbon emissions throughout their entire lifecycle while achieving complete transparency of the internal carbon footprint structure. Different modules can be selected to output the desired carbon emissions of the accounting object according to different needs. Furthermore, by embedding quantitative analysis of uncertainty into the accounting process, unlike existing methods that only focus on data input, this invention embeds data uncertainty level assessment (high, medium, low) as metadata into each data collection step. Through an error propagation model, it achieves bottom-up, step-by-step quantification and aggregation of uncertainty in a modular accounting system. The final output is not only carbon emission values, but also quantitative results with confidence intervals (i.e., uncertainty levels), enabling the simultaneous assessment of emissions and data reliability. This provides a quantitative basis for risk in high-risk decisions such as carbon trading, carbon neutrality commitments, and low-carbon technology investments.

[0061] This invention establishes a standardized and reusable accounting framework that supports multi-scenario, dynamic, and in-depth comparative analysis, empowering scientific management and industry benchmarking. Based on this unified output format, it can automatically complete three core analyses: contribution rate analysis within a project, cross-project intensity benchmarking, and attribution of the effects of emission reduction measures. Furthermore, whether comparing the energy efficiency levels of different lines or quantifying the specific effectiveness of a particular energy-saving renovation, all comparisons can be conducted under the same benchmark, ensuring fairness and scientific rigor.

[0062] This invention establishes a complete closed loop from carbon data collection to carbon management decision-making, realizing the engineering practicality of carbon accounting tools and the intelligentization of decision support. This invention is not an isolated data processing algorithm, but a complete engineering solution. It begins with practical engineering divisions, guides specific data collection, incorporates quality control and risk alerts, and ultimately serves multi-dimensional evaluation and optimization decisions. This closed-loop design greatly enhances the method's engineering practicality and user-friendliness. Attached Figure Description

[0063] To make the objectives, technical solutions, and advantages of the invention clearer, the invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0064] Figure 1 and Figure 2 The logic block diagram and flowchart of the modular rail transit carbon emission accounting method are provided.

[0065] Figure 3 This is a schematic diagram of the accounting boundaries for each stage.

[0066] Figure 4 A schematic diagram illustrating the division of the smallest module level for calculating sub-items of the project.

[0067] Figure 5 A flowchart illustrating the workflow for carbon emission calculations and uncertainty analysis. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but only to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0069] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. In addition, the terms "horizontal," "vertical," etc., do not mean that the component is required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0070] The following detailed explanation illustrates the specific implementation methods:

[0071] Example:

[0072] This embodiment discloses a modular method for calculating carbon emissions from rail transit.

[0073] like Figure 1 and Figure 2 As shown, a modular method for calculating carbon emissions from rail transit includes:

[0074] S1: Obtain pending rail transit carbon emission accounting projects;

[0075] S2: Based on the carbon emission accounting project for rail transit, extract several main accounting modules;

[0076] S3: Based on the carbon emission accounting project for rail transit, extract several accounting stage modules at the lower level of each accounting main module;

[0077] In this embodiment, it is also necessary to further determine the accounting boundaries of each accounting stage module. The accounting boundaries of each stage are as follows: Figure 3 As shown.

[0078] S4: Based on the carbon emission accounting project for rail transit, extract several accounting scope modules at the lower level of each accounting stage module;

[0079] S5: Based on the various accounting main modules, accounting stage modules and accounting scope modules in the rail transit carbon emission accounting project, several accounting sub-project minimum modules (i.e. carbon emission sources in actual projects) are obtained.

[0080] S6: Perform carbon emission calculations and uncertainty analysis on the smallest modules of each accounting sub-item of the rail transit carbon emission accounting project to obtain the carbon emission accounting results and uncertainty levels of each smallest module of the accounting sub-item;

[0081] S7: Based on the carbon emission accounting results and uncertainty levels of the smallest modules of each accounting sub-project in the rail transit carbon emission accounting project, generate corresponding carbon emission characteristic analysis results.

[0082] In this embodiment, the accounting stage module (i.e., the entire life cycle) is used as the time boundary, and the process of dividing the main accounting module into the smallest accounting sub-project module is used as the physical boundary.

[0083] To better illustrate the technical solution of the present invention, this embodiment will be described in more detail through the following parts.

[0084] I. Accounting Main Module

[0085] In this embodiment, the main accounting module includes station A1, track line A2, and vehicle depot A3.

[0086] II. Accounting Phase Module (Lifecycle Phase)

[0087] In this embodiment, the accounting phase module includes construction preparation phase B1 (phase one), construction phase B2 (phase two), and operation management phase B3 (phase three).

[0088] in:

[0089] Construction Preparation Phase B1 (Phase One): The production and transportation phase of building materials, other related non-production equipment, and related production equipment required for construction and major repairs. This phase focuses on "hidden carbon," covering the manufacturing process of all permanent materials and equipment required for rail transit projects (such as steel, cement, concrete, overhead contact line cables, air conditioning equipment, production equipment, etc.), as well as the transportation of these materials and equipment from the production site to the construction site. This generally falls under the category of upstream carbon emissions in rail transit construction.

[0090] Construction Phase B2 (Phase Two): The construction phase involving periodic major overhauls. This phase primarily focuses on carbon emissions from the energy consumption of machinery at the construction site, covering direct and indirect carbon emissions from the energy consumption of on-site machinery and temporary construction facilities during the construction period of rail transit projects, as well as other indirect emissions from the transportation and disposal of waste during construction.

[0091] Operation and Management Phase B3 (Phase Three): Operation and Management Phase. This phase mainly focuses on the direct or indirect carbon emissions from energy consumption resulting from maintaining the continuous, stable, and normal operation of the rail transit system, as well as other indirect emissions from the use of municipal water. In addition, there is carbon emission reduction from rail greening.

[0092] III. Accounting Scope Module

[0093] In this embodiment, the accounting scope module includes direct carbon emissions C1-C3 (scope one), indirect carbon emissions C4-C6 (scope two), and other indirect carbon emissions C7-C9 (scope three).

[0094] in:

[0095] Direct carbon emissions C1-C3: Direct carbon emissions at each stage of the life cycle refer to emission sources owned or controlled by relevant entities during the construction of the rail transit system, such as emissions from fuel combustion of on-site transportation and construction vehicles during stage B2.

[0096] Indirect carbon emissions C4-C6: Indirect carbon emissions at each stage of the life cycle refer to the carbon emissions generated by relevant entities through procurement or other means during the construction of the rail transit system, such as emissions generated by electricity and heat production within the site using the power grid during stage B2.

[0097] Other indirect carbon emissions (C7-C9): Other indirect carbon emissions at each stage of the life cycle refer to indirect emissions in other forms besides direct and indirect emissions, such as emissions generated from the mining and production of building materials and the transportation of raw materials and building materials in stage B1.

[0098] IV. Minimum Module for Accounting Sub-projects

[0099] Combination Figure 4 As shown, the smallest module for calculating sub-projects (carbon emission sources in actual projects) includes:

[0100] 1) The minimum module for the accounting of direct carbon emissions in the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3 includes: None;

[0101] 2) The minimum module for the accounting of indirect carbon emissions in the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3 includes: None;

[0102] 3) The minimum module for the accounting of other indirect carbon emissions C7 in the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3 includes: (mainly) carbon emission accounting items for building material production, vehicle construction, precast concrete construction, waterproof material production, rail production, safety protection material production, electrical equipment production, air conditioning system equipment production, lighting system equipment production, water supply and drainage equipment production, intelligent building equipment production and / or other related equipment production and corresponding material transportation;

[0103] 4) The minimum module for the accounting of direct carbon emissions C2 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for fuel of preliminary survey equipment, fuel of on-site transportation equipment, fuel of construction machinery, fuel of office and living area equipment, gas of temporary heating system, gas of welding operation and / or gas of small machinery.

[0104] 5) The minimum module for the accounting of indirect carbon emissions C5 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for electricity consumption of on-site machinery and equipment, electricity consumption of equipment trial operation, electricity consumption of office and living areas, heat consumption of production and processing equipment and / or heat consumption of office and living areas.

[0105] 6) The minimum module for the accounting of other indirect carbon emissions C8 during the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in office and living area and / or waste transportation and treatment during construction.

[0106] 7) The minimum module for the direct carbon emission accounting of the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting of heating system gas, domestic hot water system gas, cooking system gas, backup power fuel oil, emergency system fuel oil and / or maintenance equipment fuel oil.

[0107] 8) The minimum module for the accounting of indirect carbon emissions C6 in the operation and management phase B3 of station A1 / railway line A2 / vehicle depot A3 includes: electricity consumption for heating, air conditioning and ventilation systems, electricity consumption for lighting systems, electricity consumption for water supply and drainage systems, electricity consumption for elevator systems, electricity consumption for cooking systems, electricity consumption for indoor electrical equipment, electricity consumption for building intelligent monitoring systems, electricity consumption for train traction systems, electricity consumption for operating vehicles, electricity consumption for other special energy requirements, heat consumption for centralized heating systems, heat consumption for centralized domestic hot water systems and / or cooling consumption for centralized cooling systems;

[0108] 9) The minimum module for the accounting of other indirect carbon emissions C9 in the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in living and office area and / or greening maintenance.

[0109] V. Carbon Emission Calculation and Uncertainty Analysis

[0110] Combination Figure 5 As shown, the carbon emission accounting results and uncertainty level of the smallest module of the accounting sub-project are calculated through the following steps:

[0111] S601: Determine the carbon emission factors and activity data required for calculating the carbon emissions of the smallest module of the sub-project based on the carbon emission factor method;

[0112] In this embodiment, a multi-level accounting indicator system list is constructed based on the previous module division. Then, combined with the carbon emission accounting method used—the emission factor method—the data indicators that need to be collected are clarified, and the availability of data is ensured by combining relevant information.

[0113] S602: Calculate the carbon emissions of the smallest module of the sub-project based on carbon emission factors and activity data;

[0114] S603: Determine the individual uncertainty level of carbon emission factors and activity data, and map the individual uncertainty level to the corresponding individual relative uncertainty.

[0115] The individual uncertainty levels of carbon emission factors and activity data include low uncertainty, medium uncertainty, and high uncertainty, with corresponding individual relative uncertainties of 5%, 15%, and 25%, respectively. The individual uncertainty levels of carbon emission factors and activity data are determined based on their sources.

[0116] High uncertainty: Data based on common assumptions, early predictions, non-specific sources, or lack of transparency and verification, with weak correlation between the data and the accounting object, will lead to high uncertainty in the results when using such data to calculate carbon emissions. This includes: bills of quantities in the preliminary design stage, lists of experience data referencing similar projects, lists of data formed by relevant standards issued by governments or industries, and carbon emission factors in internationally recognized databases such as the IPCC.

[0117] Medium uncertainty: The data has good basic quality, but there is a transformation or allocation relationship between it and the specific accounting object of the application. It needs to be associated with reasonable assumptions or models. Using such data requires the introduction of additional assumptions, which leads to a medium degree of uncertainty in the calculation results. These include: the entry and exit records of the engineering site, the energy consumption allocation based on total energy consumption and the proportion of related studies, the national grid average emission factor, and the carbon emission factor in the China Life Cycle Basic Database (CLCD).

[0118] Low uncertainty: The data comes from direct, specific physical measurements and is fully matched to the accounting object. It usually has a complete calibration, correction and audit trail. The carbon emissions obtained using such data have low uncertainty, including: the usage of key building materials verified by multiple parties, energy consumption data measured by independent metering instruments, carbon emission factors based on product EPD (Environmental Product Declaration Certification), and factors based on specific power sources.

[0119] Specifically, based on the uncertainty level of the input data in the smallest module of each accounting sub-item, the quantified uncertainty is determined. For each smallest module of the accounting sub-item, based on the quantified uncertainty of all its input data, the combined uncertainty of the module's output result is calculated through the error propagation model. According to the hierarchical relationship of the accounting modules, the combined uncertainty is aggregated from bottom to top to finally obtain the uncertainty of the total carbon emission result of the project.

[0120] S604: Calculate the relative combined standard uncertainty of the smallest module of the sub-project based on the individual relative uncertainty of carbon emission factors and activity data;

[0121] S605: Determine the uncertainty level of the smallest module of a sub-project based on the relative combined standard uncertainty assessment;

[0122] The uncertainty levels of carbon emissions are categorized into low, medium, and high: a relative combined standard uncertainty of less than or equal to 10% corresponds to a low uncertainty level; a relative combined standard uncertainty of greater than 10% and less than or equal to 25% corresponds to a medium uncertainty level; and a relative combined standard uncertainty of greater than 25% corresponds to a high uncertainty level.

[0123] S606: Expand the relative combined standard uncertainty of the smallest module of the accounting sub-item project to obtain the relative expanded uncertainty;

[0124] S607: Calculate the corresponding accounting error based on the carbon emissions and relative expanded uncertainty of the smallest module of the accounting sub-project;

[0125] S608: Calculate the corresponding carbon emission accounting results based on the carbon emission of the smallest module of the accounting sub-project and the accounting error.

[0126] Wherein, carbon emission accounting result = carbon emission amount ± accounting error amount;

[0127] S609: Output the carbon emission calculation results and uncertainty level of the smallest module of the accounting sub-project.

[0128] Specifically, carbon emissions are calculated using the following formula:

[0129] ;

[0130] In the formula: Indicates carbon emissions; Represents activity data; Indicates carbon emission factor.

[0131] Specifically, the relative combined standard uncertainty is calculated using the following formula:

[0132] ;

[0133] In the formula: This represents the relative combined standard uncertainty; This represents the individual relative uncertainty of the activity data; This represents the individual relative uncertainty of the carbon emission factor.

[0134] Specifically, the relative expanded uncertainty is calculated using the following formula:

[0135] ;

[0136] In the formula: This represents the relative expanded uncertainty; This represents the relative combined standard uncertainty; This represents the expansion factor, which is set to 2.

[0137] Specifically, the accounting error is calculated using the following formula:

[0138] ;

[0139] In the formula: Indicates the amount of accounting error; This represents the relative expanded uncertainty; This indicates carbon emissions.

[0140] In the specific implementation process, after calculating the carbon emission accounting results and uncertainty level of the smallest module of each accounting sub-item project, the following calculations are performed:

[0141] 1) The carbon emission calculation results of all the smallest modules of the accounting sub-projects under the accounting scope module are summed to obtain the carbon emission calculation result of the accounting scope module. At the same time, the relative expanded uncertainty of all the smallest modules of the accounting sub-projects is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting scope module. The uncertainty level of the accounting scope module is determined based on the expanded uncertainty.

[0142] Among them, error propagation calculation refers to: summing up the squares of the relative expanded uncertainty of the smallest module of all accounting sub-items and then performing square root calculation;

[0143] 2) The carbon emission accounting results of all accounting scope modules under the accounting stage module are summed to obtain the carbon emission accounting result of the accounting stage module. At the same time, the expanded uncertainty of all accounting scope modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting stage module. The uncertainty level of the accounting stage module is determined based on the expanded uncertainty.

[0144] 3) The carbon emission accounting results of all accounting stage modules under the main accounting module are summed to obtain the carbon emission accounting result of the main accounting module. At the same time, the expanded uncertainty of all accounting stage modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the main accounting module. The uncertainty level of the main accounting module is determined based on the expanded uncertainty.

[0145] 4) The carbon emission accounting results of all accounting modules under the rail transit carbon emission accounting project are summed to obtain the carbon emission accounting result of the rail transit carbon emission accounting project. At the same time, the expanded uncertainty of all accounting modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the rail transit carbon emission accounting project. The uncertainty level of the rail transit carbon emission accounting project is determined based on the expanded uncertainty.

[0146] This invention outputs carbon emission accounting results and their uncertainty levels at multiple levels, including the accounting subject module, accounting stage module, and accounting scope module. This enables the simultaneous assessment of emissions and data reliability, providing a quantitative basis for high-risk decisions such as carbon trading, carbon neutrality commitments, and low-carbon technology investments.

[0147] VI. Analysis of Carbon Emission Characteristics

[0148] In this embodiment, three specific analysis types are designed, including:

[0149] 1) Project-specific characteristics analysis: This is used to analyze the carbon emission structure of rail transit projects. By accepting the calculation results of each level of modules, it calculates the proportion of each sub-item's carbon emissions to the total emissions of the project's entire life cycle, as well as the emission proportion of each sub-module within its superior module. This optimizes the carbon emission contribution rate of each module. Based on this contribution rate, key carbon emission modules or high carbon emission items in the project can be identified.

[0150] 2) Inter-project comparative analysis: This is used to assess the differences in carbon emission intensity between different rail transit projects or other modes of transportation. First, the calculation results of different projects or other modes of transportation are standardized to carbon emission intensity based on the same functional unit. Then, this intensity can be compared with industry benchmarks, theoretical optimal values, or the average values ​​of other projects. When conducting cross-category comparisons, it is necessary to set a unified accounting boundary for the operating period and select functionally equivalent modules for analysis.

[0151] 3) Emission Reduction Effect Analysis: Used to quantitatively evaluate the actual effectiveness of carbon reduction measures. This analysis compares the accounting results of the same rail transit project (commonly seen in green energy-saving retrofits of existing lines) before and after the implementation of specific carbon reduction measures. It identifies specific accounting modules that are directly affected by the measures and changes accordingly, thereby accurately quantifying the emission reduction amount or proportion brought about by the measures and making an objective assessment of their effects.

[0152] To better illustrate the advantages of the technical solution of the present invention, the following two examples are disclosed in this embodiment.

[0153] Example 1:

[0154] 1. Determine the accounting subject, that is, clarify the accounting subject module to which the carbon emission accounting object belongs. For this example, what needs to be accounted for is the carbon emission of the entire urban rail transit project. Latitude-wise, it includes all stages of the entire life cycle, and longitude-wise, it includes stations, lines, and vehicle depots. Therefore, the accounting subject modules it includes are: stations, lines, and vehicle depots, namely, modules A1-A3.

[0155] 2. Determine the accounting modules, that is, determine the modules under the main module. For this example, the carbon emissions of the entire urban rail transit project need to be calculated. Therefore, the modules to which the accounting content belongs should include the three modules B1-B3 for the entire life cycle, the nine scope modules C1-C9 for the next level of emission sources, and the module for all sub-projects.

[0156] 3. Clearly define the lowest-level carbon emission module included in the accounting, i.e., the emission source module. For this example, to illustrate the composition of the smallest module, some typical smallest modules are selected below as examples (this invention is not limited to these):

[0157] A1B1C3 Production sub-items of major building materials: Carbon emissions generated from the production of C30 concrete;

[0158] A1B2C4 On-site Machinery Electricity Consumption Sub-item: Carbon emissions generated from electricity production for tunnel boring machines;

[0159] A2B3C6 Train traction electricity consumption (in years): Carbon emissions generated from the production of electricity for train traction.

[0160] 4. After determining all the sub-items that need to be included, construct an accounting indicator system using the module and its parent module. Combine this with the applicable carbon emission factor method to clarify the data indicators that need to be collected in the project and to reasonably define the units of these indicators. According to this embodiment, to illustrate the data indicators that need to be collected, some typical data types are selected as examples below (this invention is not limited to these):

[0161] A1B1C3 Production of major building materials: Carbon emissions from the production of C30 concrete. According to the carbon emission factor method, the data indicators required for this sub-item include the carbon emission factor (kgCO2e / m³) of the C30 concrete production process and the activity data corresponding to the emission factor, as well as the amount of C30 concrete used (m³).

[0162] A1B2C4 On-site Machinery Electricity Consumption Sub-item: Carbon emissions generated from electricity production for tunnel boring machines. According to the carbon emission factor method, the data indicators required for this sub-item include the carbon emission factor (kgCO2e / kWh) of the purchased electricity production process and the activity data corresponding to the emission factor, as well as the electricity consumption (kWh) of tunnel boring machine construction.

[0163] A2B3C6 Train Traction Electricity Consumption Sub-item (in years): Carbon emissions generated from the production of electricity for train traction. According to the carbon emission factor method, the data indicators required for this sub-item include the carbon emission factor (kgCO2e / kWh) of the purchased electricity production process and the activity data corresponding to the emission factor, and the electricity consumption of train traction per unit time (year) (kWh).

[0164] 5. Collect data according to the accounting indicator system table, ensuring the integrity and uniformity of the data, and label the source of the data collection.

[0165] 6. Based on the data source, perform uncertainty analysis on the modularized accounting results, and then further calculate the uncertainty of the module using the error propagation model. In this embodiment, to illustrate the uncertainty analysis of the data, the uncertainty analysis of a typical module is selected as an example below (this invention is not limited to this):

[0166] Production items for major building materials A1B1C3:

[0167] First, assign values ​​to the uncertainty levels of the data. The relative uncertainty range for a low uncertainty level is ≤10%, the relative uncertainty range for a medium uncertainty level is >10% and ≤25%, and the relative uncertainty range for a high uncertainty level is >25% (this is just an example assignment).

[0168] The carbon emission factor of C30 concrete production is 295 kg CO2e / m³, data source: GB / T 51366-2019 "Standard for Calculation of Building Carbon Emissions"; the amount of C30 concrete used is 129 m³, data source: assumed value, and it is assumed that its source is the construction log at the construction site. Based on the data source, the uncertainty level of the carbon emission factor is assessed as medium, and the uncertainty of the activity data is medium. According to the predefined mapping rule (taking the relative standard uncertainty corresponding to the 'medium' level as 15%), the relative combined standard uncertainty of the carbon emissions of this module is calculated using the error propagation formula of the multiplicative model, and the uncertainty level of this module is assessed as medium. Finally, the carbon emissions of this module are reported as 38.06 ± 16.14 tCO2e (coverage factor k = 2).

[0169] 7. Based on the carbon emission accounting results output by each module and the uncertainty level of the results, clarify the carbon emission characteristics within the relevant projects. Simultaneously, based on different data inputs, comparisons can be made between different projects and between projects to assess the emission reduction effects, evaluating the low-carbon effects of rail transit and the effectiveness of its carbon reduction measures and strategies.

[0170] Example 2:

[0171] 1. Determine the accounting subject, that is, clarify the accounting subject module to which the carbon emission accounting object belongs. For this example, the carbon emissions to be calculated are the carbon emissions during the operation period of urban rail transit. In terms of latitude, it includes the operation period throughout the entire life cycle, and in terms of longitude, it includes stations, lines, and vehicle depots. Therefore, the accounting subject modules it includes are: stations, lines, and vehicle depots, namely modules A1-A3.

[0172] 2. Determine the accounting modules, that is, determine the modules under the main module. For this example, the carbon emissions to be calculated are for the operation period of urban rail transit. Therefore, the modules to which the accounting content belongs should include the B3 module for the entire life cycle, the three scope modules C3, C6, and C9 for the next level of emission source scope, and the corresponding sub-item engineering modules at the next level.

[0173] 3. Clearly define the lowest-level carbon emission module included in the accounting, i.e., the emission source module. For this example, to illustrate the composition of the smallest module, some typical smallest modules are selected below as examples (this invention is not limited to these):

[0174] A1B3C3 Station Heating Gas Consumption Breakdown (by Year): Carbon Emissions from Station Gas Heating

[0175] A2B3C6 Train traction power consumption (in years): Carbon emissions generated from the production of electricity for train traction;

[0176] A1B3C9 Station cleaning water usage breakdown (in years): Carbon emissions from municipal water treatment for station cleaning.

[0177] 4. After determining all the sub-items that need to be included, construct an accounting indicator system using the module and its parent module. Combine this with the applicable carbon emission factor method to clarify the data indicators that need to be collected in the project and to reasonably define the units of these indicators. According to this embodiment, to illustrate the data indicators that need to be collected, some typical data types are selected as examples below (this invention is not limited to these):

[0178] A1B3C3 Station Heating Gas Consumption Sub-item (in years): Carbon emissions generated by station gas heating. According to the carbon emission factor method, the data indicators required for this sub-item include the carbon emission factor of the natural gas combustion process (kgCO2 / TJ) and the activity data corresponding to the emission factor, as well as the product of the natural gas consumption and its calorific value (TJ).

[0179] A2B3C6 Train Traction Electricity Consumption Sub-item (in years): Carbon emissions generated from the production of electricity for train traction; According to the carbon emission factor method, the data indicators required for this sub-item include the carbon emission factor of the electricity production process (kgCO2 / kWh) and the activity data corresponding to the emission factor, as well as the electricity consumption (kWh).

[0180] A1B3C9 Station Cleaning Water Use Item (in annual units): Carbon emissions from municipal water treatment for station cleaning. According to the carbon emission factor method, the data indicators required for this item include the carbon emission factor of the municipal water treatment process (kgCO2 / m³) and the activity data corresponding to the emission factor, as well as the amount of natural gas used (m³).

[0181] 5. Collect data according to the accounting indicator system table, ensuring the integrity and uniformity of the data, and label the source of the data collection.

[0182] 6. Based on the data source, perform uncertainty analysis on the modularized accounting results, and then further calculate the uncertainty of the module using the error propagation model. In this embodiment, to illustrate the uncertainty analysis of the data, the uncertainty analysis of a typical module is selected as an example below (this invention is not limited to this):

[0183] Traction power consumption of train A2B3C6 (in yearly units):

[0184] First, assign values ​​to the uncertainty levels of the data. The relative uncertainty range for a low uncertainty level is ≤10%, the relative uncertainty range for a medium uncertainty level is >10% and ≤25%, and the relative uncertainty range for a high uncertainty level is >25% (this is just an example assignment).

[0185] In 2024, China's electricity carbon footprint factor was 0.5777 kgCO2e / kWh, data source: published on the official website of the Ministry of Ecology and Environment of the People's Republic of China; the annual electricity consumption of this section was 30,000 kWh, data source: an assumed value, and it is assumed that its source is allocated from data in publicly available reports. Based on the data source, the carbon emission factor is assessed as medium, and the uncertainty level of the activity data is medium. According to the predefined mapping rule (taking the relative standard uncertainty corresponding to the 'medium' level as 15%), the relative combined standard uncertainty of the carbon emissions of this module is calculated using the error propagation formula of the multiplicative model, and the uncertainty level of this module is assessed as medium. Finally, the carbon emissions of this module are reported as 17.331 ± 7.35 tCO2e (coverage factor k=2).

[0186] 7. Based on the carbon emission accounting results output by each module and the uncertainty level of the results, clarify the carbon emission characteristics within the relevant projects. Simultaneously, based on different data inputs, comparisons can be made between different projects and between projects to assess the emission reduction effects, evaluating the low-carbon effects of rail transit and the effectiveness of its carbon reduction measures and strategies.

[0187] In summary, the modular carbon emission accounting method for rail transit proposed in this invention, through the construction of a multi-level, multi-dimensional modular system consisting of "accounting main module - accounting stage module - accounting scope module - accounting sub-project minimum module (i.e., carbon emission source module of accounting sub-project)," achieves for the first time in the industry a transparent analysis of the entire life cycle and all aspects of carbon emissions from complex rail transit systems. This method not only incorporates international standard Scope I, Scope II, and Scope III emissions into a unified framework, but also creatively embeds data quality assessment and uncertainty quantification analysis into the accounting process. By assigning a clear uncertainty level to each input data point and achieving bottom-up, step-by-step quantification and aggregation of uncertainty based on the error propagation law, it outputs scientific carbon accounting results with confidence intervals (i.e., uncertainty levels). This invention is not only an accounting tool, but also a scalable and reusable carbon data management benchmark platform. Through standardized and structured output, it enables in-depth analysis of high-carbon emission items within projects, multi-directional comparisons, and attribution of the effects of emission reduction measures. The design of this invention balances accuracy and flexibility. Its modular architecture can easily adapt to different types of rail transit projects (such as subways, light rail, and urban rail), different data availability conditions, and new scenarios that may emerge in the future.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A modular method for calculating carbon emissions from rail transit, characterized in that, include: S1: Obtain pending rail transit carbon emission accounting projects; S2: Based on the carbon emission accounting project for rail transit, extract several main accounting modules; S3: Based on the carbon emission accounting project for rail transit, extract several accounting stage modules at the lower level of each accounting main module; S4: Based on the carbon emission accounting project for rail transit, extract several accounting scope modules at the lower level of each accounting stage module; S5: Based on the various accounting main modules, accounting stage modules, and accounting scope modules in the rail transit carbon emission accounting project, several minimum modules of accounting sub-projects are obtained; S6: Perform carbon emission calculations and uncertainty analysis on the smallest modules of each accounting sub-project of the rail transit carbon emission accounting project to obtain the corresponding carbon emission accounting results and uncertainty levels; S7: Based on the carbon emission accounting results and uncertainty levels of the smallest modules of each accounting sub-project in the rail transit carbon emission accounting project, generate corresponding carbon emission characteristic analysis results.

2. The modular rail transit carbon emission accounting method as described in claim 1, characterized in that: In step S2, the main accounting module includes station A1, track line A2 and / or vehicle depot A3.

3. The modular rail transit carbon emission accounting method as described in claim 2, characterized in that: In step S3, the accounting phase module includes the construction preparation phase B1, the construction phase B2, and / or the operation and management phase B3.

4. The modular rail transit carbon emission accounting method as described in claim 3, characterized in that: In step S4, the accounting scope module includes direct carbon emissions C1-C3, indirect carbon emissions C4-C6, and other indirect carbon emissions C7-C9.

5. The modular rail transit carbon emission accounting method as described in claim 4, characterized in that: In step S5, the minimum module for calculating the sub-item project includes: 1) Direct carbon emissions of the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3; C1 is the smallest module of the unaccounted sub-project. 2) Indirect carbon emissions of the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3; C4 is the smallest module of the unaccounted sub-project. 3) The minimum module for the accounting of other indirect carbon emissions C7 in the construction preparation phase B1 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for building material production, vehicle construction, precast concrete construction, waterproof material production, rail production, safety protection material production, electrical equipment production, air conditioning system equipment production, lighting system equipment production, water supply and drainage equipment production, intelligent building equipment production and / or other related equipment production and corresponding material transportation; 4) The minimum module for the accounting of direct carbon emissions C2 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for fuel of preliminary survey equipment, fuel of on-site transportation equipment, fuel of construction machinery, fuel of office and living area equipment, gas of temporary heating system, gas of welding operation and / or gas of small machinery. 5) The minimum module for the accounting of indirect carbon emissions C5 in the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for electricity consumption of on-site machinery and equipment, electricity consumption of equipment trial operation, electricity consumption of office and living areas, heat consumption of production and processing equipment and / or heat consumption of office and living areas. 6) The minimum module for the accounting of other indirect carbon emissions C8 during the construction phase B2 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in office and living area and / or waste transportation and treatment during construction. 7) The minimum module for the direct carbon emission accounting of the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting of heating system gas, domestic hot water system gas, cooking system gas, backup power fuel oil, emergency system fuel oil and / or maintenance equipment fuel oil. 8) The minimum module for the accounting of indirect carbon emissions C6 in the operation and management phase B3 of station A1 / railway line A2 / vehicle depot A3 includes: electricity consumption for heating, air conditioning and ventilation systems, electricity consumption for lighting systems, electricity consumption for water supply and drainage systems, electricity consumption for elevator systems, electricity consumption for cooking systems, electricity consumption for indoor electrical equipment, electricity consumption for building intelligent monitoring systems, electricity consumption for train traction systems, electricity consumption for operating vehicles, electricity consumption for other special energy requirements, heat consumption for centralized heating systems, heat consumption for centralized domestic hot water systems and / or cooling consumption for centralized cooling systems; 9) The minimum module for the accounting of other indirect carbon emissions C9 in the operation and management phase B3 of station A1 / track line A2 / vehicle depot A3 includes: carbon emission accounting items for water use in production area, water use in living and office area and / or greening maintenance.

6. The modular rail transit carbon emission accounting method as described in claim 1, characterized in that: In step S6, the carbon emission calculation results and uncertainty level of the smallest module of the accounting sub-project are calculated through the following steps: S601: Determine the carbon emission factors and activity data required for calculating the carbon emissions of the smallest module of the sub-project based on the carbon emission factor method; S602: Calculate the carbon emissions of the smallest module of the sub-project based on carbon emission factors and activity data; The formula is expressed as: ； In the formula: Indicates carbon emissions; Represents activity data; Indicates carbon emission factor; S603: Determine the individual uncertainty level of carbon emission factors and activity data, and map the individual uncertainty level to the corresponding individual relative uncertainty. S604: Calculate the relative combined standard uncertainty of the smallest module of the sub-project based on the individual relative uncertainty of carbon emission factors and activity data; S605: Determine the uncertainty level of the smallest module of a sub-project based on the relative combined standard uncertainty assessment; S606: Expand the relative combined standard uncertainty of the smallest module of the accounting sub-item project to obtain the relative expanded uncertainty; S607: Calculate the corresponding accounting error based on the carbon emissions and relative expanded uncertainty of the smallest module of the accounting sub-project; S608: Calculate the corresponding carbon emission accounting results based on the carbon emission of the smallest module of the accounting sub-project and the accounting error. Wherein, carbon emission accounting result = carbon emission amount ± accounting error amount; S609: Output the carbon emission calculation results and uncertainty level of the smallest module of the accounting sub-project.

7. The modular rail transit carbon emission accounting method as described in claim 6, characterized in that: In step S604, the relative combined standard uncertainty is calculated using the following formula: ； In the formula: This represents the relative combined standard uncertainty; This represents the individual relative uncertainty of the activity data; This represents the individual relative uncertainty of the carbon emission factor.

8. The modular rail transit carbon emission accounting method as described in claim 6, characterized in that: In step S606, the relative expanded uncertainty is calculated using the following formula: ； In the formula: This represents the relative expanded uncertainty; This represents the relative combined standard uncertainty; This represents the expansion factor.

9. The modular rail transit carbon emission accounting method as described in claim 6, characterized in that: In step S607, the accounting error is calculated using the following formula: ； In the formula: Indicates the amount of accounting error; This represents the relative expanded uncertainty; This indicates carbon emissions.

10. The modular rail transit carbon emission accounting method as described in claim 6, characterized in that: In step S6, after calculating the carbon emission accounting results and uncertainty level of the smallest module of each accounting sub-item, the following calculations are performed: 1) The carbon emission calculation results of all the smallest modules of the accounting sub-projects under the accounting scope module are summed to obtain the carbon emission calculation result of the accounting scope module. At the same time, the relative expanded uncertainty of all the smallest modules of the accounting sub-projects is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting scope module. The uncertainty level of the accounting scope module is determined based on the expanded uncertainty. 2) The carbon emission accounting results of all accounting scope modules under the accounting stage module are summed to obtain the carbon emission accounting result of the accounting stage module. At the same time, the expanded uncertainty of all accounting scope modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the accounting stage module. The uncertainty level of the accounting stage module is determined based on the expanded uncertainty. 3) The carbon emission accounting results of all accounting stage modules under the main accounting module are summed to obtain the carbon emission accounting result of the main accounting module. At the same time, the expanded uncertainty of all accounting stage modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the main accounting module. The uncertainty level of the main accounting module is determined based on the expanded uncertainty. 4) The carbon emission accounting results of all accounting modules under the rail transit carbon emission accounting project are summed to obtain the carbon emission accounting result of the rail transit carbon emission accounting project. At the same time, the expanded uncertainty of all accounting modules is calculated by error propagation and multiplied by the expansion factor to obtain the expanded uncertainty of the rail transit carbon emission accounting project. The uncertainty level of the rail transit carbon emission accounting project is determined based on the expanded uncertainty.

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