Allocation at the point of substitution applied to recycled rare earth elements: what can we learn?

Purpose Partitioning is often recommended as allocation procedure in attributional Life Cycle Assessments (a-LCAs). However, little guidance is available on how to apply partitioning to recycled products. This paper aims to demonstrate and discuss the application of the allocation procedure allocation at the point of substitution (APOS) via an evaluation of the impacts of the recycled phosphor yttrium europium oxide (YOX) from end-of-life fluorescent lamps. Methods Starting from a multifunctional recycling process, APOS is applied by (1) identifying the products of the foreground sub-system, (2) identifying the origin of the recycled waste, (3) defining the boundaries of the production systems, and (4) applying economic allocation. Results and discussion It appears that recycled YOX is accountable for lower impacts than primary YOX for most impact categories. The largest contributor to the impacts of recycled YOX are the impacts related to the primary production of the fluorescent lamp, such as the use of mercury in the lamp tube. Even if this can be counter-intuitive to accept-as these impacts seem unrelated to YOX-these results provide useful information on whether the supply route of rare earth elements (REEs) from end-of-life fluorescent lamps is future proof, regarding potential (supply) risks due to environmental impacts upstream in the product supply chain. Conclusions The application of APOS is demonstrated on the end-of-life recycling of rare earth elements. APOS provides the user of the recycled REE information about environmental impacts upstream in the product's value chain. This could inform about the sustainability of the company's operations-i.e., whether the future use or production of a material might be compromised due to (regulations to decrease) environmental impacts.

Automated summary

This paper demonstrates and discusses the application of allocation procedure allocation at the point of substitution (APOS) on recycled products, showing that recycled YOX has lower impacts than primary YOX for most impact categories. The study provides useful information on the future sustainability of rare earth element supply chains.