Waste Input-Output Material Flow Analysis of Metals and Plastics in the Japanese Economy

摘要

A general analytical model of MFA in the form of a physical Waste Input-Output (Nakamura and Kondo (2002)) is proposed that is fully consistent with the mass balance principle. Exploiting the triangular nature of the matrix of input coefficients, which is obtained by rearranging the ordering of sectors according to degrees of fabrication, the material composition matrix is derived that gives the material composition of products. By use of this matrix, monetary input-output tables (MIOT) can easily be converted into a physical material flow account (or physical input-output tables, PIOT) of an arbitrary number of materials, and the material composition of a product can be decomposed into its input origin. This facilitates a simultaneous MFA for an arbitrary number of materials, whereas the conventional MFA considers only one material at a time. The proposed methodology is applied to Japanese IO data of more than four hundred industry sectors for the flow of eleven base metals and nine types of plastics including scrap. The explanatory power of the methodology is tested for the weight and material composition of a passenger car. Final destination of plastics (PVC) by products and final demand categories is also estimated.