Mapping Aluminum Flows in the United States using Bayesian Material Flow Analysis

This paper presents a Bayesian material flow analysis (MFA) of aluminum in the U.S. economy, reconciling a 2017 baseline and updating the system to 2022. We introduce ARCADE (Abiotic Resource Cycles, Allocations, and Dynamics in the Economy), a unified Bayesian MFA framework that integrates system definition, data pedigree, and probabilistic reconciliation under physical constraints. ARCADE combines government statistics, trade records, and industry reports into a physically consistent network and reports uncertainty-aware metrics, including recycled content, end-of-life (EOL) recycling, scrap collection, domestic retention, and stock change. Results show the U.S. (1) remains highly reliant on imports of unwrought and finished aluminum products; (2) had a slightly higher EOL scrap collection rate in 2022 (64%) than in 2017 (63%), but lower domestic retention of collected EOL scrap (52% vs. 58%), indicating a widening gap between collection and domestic use; and (3) could increase wrought-grade recycling by targeting key nodes in EOL scrap collection, domestic processing, and product allocation. Overall, improved collection does not necessarily raise domestic retention given processing constraints and continued scrap exports.