LCA of rare earth and critical metal recovery and replacement decisions for commercial lighting waste management

Abstract

Lighting waste represents a significant source of rare earth elements (REE) and critical metals (CM), which are vital to low-carbon technologies. This research examines the environmental impacts of recovering REE (Yttrium and Europium) from linear fluorescent fixtures and CM (Gallium) from linear LED fixtures, as well as the implications of technology transition (e.g., from fluorescent to LED) and replacement decisions (i.e., extended use, modular replacement/retrofits, and full replacement) on waste management. An LCA is conducted by modeling 1 million lumen-hours of service from an 8 ft T8 linear fixture across 16 pathways representing multiple replacement and waste management options. The study finds that recovering REE and CM from lamp waste via hydrometallurgical methods generally result in more environmental impacts than the primary production of the recovered materials. Per kg recovered, the global warming impact is 74 kg and 3,687 kg CO2eq for REE and Ga, respectively. The high impacts for Ga recovery are due to Ga's low concentration (0.234 w/w%) in the LED waste. Intermediate results at the end of life stage show that recycling common metals (e.g., aluminum, copper, and sometimes steel) from fixtures can reduce or even completely offset the impacts of specialty metal recovery. Based on the end results, a mature technology like fluorescent fixtures can benefit from both extended use and modular product designs. The best strategy is to prioritize energy efficiency (e.g., by upgrading to new LED) and to choose full luminaire (lamps, electronics, and fixture) upgrades, which offer higher system efficacies, over retrofits (lamps and electronics only).