Beyond mass recovery: an exergy lens for resource management

Mass-based indicators remain useful for reporting circular-economy performance, but they can give an incomplete account of complex waste streams. A kilogram of mixed recovered metal is not functionally equivalent to a kilogram retained at the purity, phase, and concentration required for reuse. This study therefore proposes a practitioner-oriented exergy screen to complement material flow analysis when recovery performance depends on preserving material quality. It distinguishes chemical exergy, cumulative production exergy, and exergy replacement cost, and clarifies that the practical burden of dispersion arises mainly from irreversible processing and re-concentration rather than from ideal mixing alone. Existing quality-sensitive methods – statistical entropy analysis, exergy-based recycling assessment, cumulative exergy accounting, and MaTrace – provide the analytical foundation. The contribution here is to translate that foundation into explicit screening triggers, a lithium-ion battery illustration, and concrete design and policy implications. This approach does not replace mass accounting. It identifies cases in which aggregate recovery should be reported alongside constituent-specific yields and, where material quality is decision-critical, a clearly bounded exergy or replacement-cost assessment.