Deriving material composition of products using life cycle inventory databases

Abstract

Understanding the detailed material composition of the various industrial and consumer products is essential for implementing efficient recycling practices and policies, conducting material flow analyses, and facilitating a transition toward a circular economy. However, existing data sources are limited in their product and material coverage. Currently, no source or methodology allows such data to be obtained in a relatively uniform, updated, and accessible manner across a diverse range of products. This work presents an approach that allows estimating the material composition of thousands of products using available life cycle inventory (LCI) databases. Methodologically, this is implemented by splitting the physical flows that describe supply chains in LCI databases into “incorporated” and “not incorporated” fractions using an incorporation parameter. Building primarily on existing matrix-based life cycle assessment calculations, this approach can be used to calculate the material content of products. A generally applicable mathematical model, as well as a ready-to-use software, is presented for future practitioners. To demonstrate the robustness of the proposed method, a case study involving three metals and plastic in three consumer goods has been conducted based on the ecoinvent database. Our method delivered accurate material content estimates (i.e., weight fractions of materials in products) with an average relative error of 26% and an absolute error of 1.1% (between our estimates and existing values).