丝绸产品碳足迹核算的关键问题讨论

Discussions on key issues of carbon footprint accounting of silk products

为准确核算丝绸产品的碳足迹,本文对核算边界、核算数据、温室气体去除、研究结果计算等关键问题进行了分析讨论。研究结果表明:选择“摇篮到大门”或“大门到大门”作为丝绸产品碳足迹的核算边界具有较好的可操作性;确定核算边界内的关键温室气体排放源,必要时选择适用的数据分配方法并保持核算边界内分配方法的一致性,可提高核算数据的质量;蚕丝生物碳的温室气体去除量可在丝绸产品碳足迹核算结果报告时单独说明;丝绸企业的碳中和行动可纳入丝绸产品的碳足迹核算结果;核算边界一致和排放因子数据一致是不同丝绸产品碳足迹计算结果可比的两个关键前提。

The green and low-carbon development of industries and green and low-carbon consumption of products are the key elements of carbon peak and carbon neutrality strategy in China.The accounting of carbon footprint of products in the life cycle provides an important reference for the carbon mitigation in the industrial production and consumption progresses.The concept of carbon footprint and the discussion about its accounting methods started around 2005,and has subsequently experienced a series of developments and refinements.There are also related institutions at home and abroad developing Product Category Rules(PCR)for product carbon footprint accounting to standardize the accounting of product carbon footprint in more detail.Silk products are are favored by consumers.China is a major producer of silkworm cocoons and raw silk,and the largest producer and processor of silk fabrics,silk garments,and silk home textile products in the world.The carbon footprint accounting of silk products is of great significance for the low carbon development of the silk industry.In order to accurately calculate the carbon footprint of silk products,the key issues such as the accounting boundary,accounting data,greenhouse gas(GHG)sequestration and result calculation were analyzed and discussed.The whole life cycle of silk products is divided into five stages,namely the acquisition of silkworm cocoons,the manufacture of products,the sales and use of products,the disposal of products and recycling.Each phase is divided into several segments.The accounting boundary of the carbon footprint of silk products can be adjusted flexibly based on the accounting purpose,but when the carbon footprint accounting results are reported and the carbon footprint of different products is compared,or the reduced carbon footprint of the same product using an optimized manufacturing process is quantified,the accounting boundary needs to be explained clearly.Accounting data are the basis of product carbon footprint accounting.The paper lists the GHG emission sources and data inventories of silk products at each stage,and gives examples of the distribution method of GHG emission sources in the accounting process.The ways of greenhouse gas sequestration involve absorbing carbon dioxide and converting it into biochar through plant photosynthesis,artificial carbon capture,storage and utilization.Generally,the use time of silk products is not more than fifty years,so the carbon dioxide sequestration of silk may not be included into the calculation of the carbon footprint of silk products.If manufacturers of silk products remove greenhouse gases from the atmosphere by purchasing carbon sinks and adopting artificial carbon capture,storage and utilization,the greenhouse gases should be calculated in the carbon footprint accounting.When the GHG emission results are calculated,chemical reaction emissions of direct greenhouse gas emissions within the accounting boundary of carbon footprint can be calculated by chemical equilibrium equation.Indirect greenhouse gas emissions within the accounting boundary can be calculated according to the method of GHG emission=AD×EF(AD represents activity data,and EF represents the emission factor),and EF data are still the key factor restricting the calculation of carbon footprint results of products.The calculation result of the carbon footprint of silk products is the sum of carbon footprints in each process within the accounting boundary,and different functional units can be set according to different product categories.In this paper,the key technologies such as boundary setting,data collection and distribution,and result calculation are systematically discussed for the carbon footprint accounting of silk products and the development of standards.The results show that it is feasible to choose“cradle to gate”or“gate to gate”as the accounting boundary of carbon footprint of silk products.The quality of accounting data can be improved by determining the key emission sources of GHG within the accounting boundary,selecting the appropriate allocation methods and maintaining the consistency of the allocation methods within the accounting boundary when necessary.The GHG sequestration of silk can be explained separately in the report of carbon footprint sequestration results of silk products;the carbon neutralization actions of silk enterprises can be incorporated in the carbon footprint quantification results of silk products;consistent accounting boundary and emission factors are two key prerequisites for the feasibility of carbon footprint quantification results of different silk products.The carbon footprint accounting of silk products provides a reference for low-carbon design of silk products,carbon emission reduction in the manufacturing process,and green and low-carbon consumption of consumers.It is also of great significance to the green and low-carbon development of the silk industry.The life cycle chain of silk products is long and involves many input and output elements.It is necessary to fully and systematically analyze the key issues of carbon footprint accounting of silk products to ensure the validity and comparability of carbon footprint accounting results.