China Factor: Exploring the Byproduct and Host Metal Dynamics for Gallium-Aluminum in a Global Green Transition.

The potential constraints of critical material supply for the global green transition have raised increasing concerns in recent years. As an important "green minor metal", gallium faces such a potential supply risk for two reasons: it is a byproduct of aluminum production, and the forthcoming end of primary aluminum production boom in China, currently the main global aluminum producer, may bring substantial impacts on the global gallium supply. Here, we investigated this byproduct and host metal linkage using a system dynamics based integrated model and characterized the gallium-aluminum dynamics in a green transition up to 2050 across five world regions (i.e., China, the United States, the European Union, Japan, and the rest of the world). Our results reveal varying patterns of gallium demand and supply in different world regions and the significant role of "the China factor" in ensuring a sustainable gallium supply globally. However, the concerns on the gallium supply risk in China for a common green future could be relieved from the coordination of mitigation strategies from both supply (primary and secondary) and demand (e.g., process efficiency improvement and material intensity reduction) sides among all world regions. Our methodological integration of system dynamics, industrial ecology, and economic geology can be extended to other materials.