Rare-earth elements (REEs) such as neodymium, praseodymium, dysprosium, and terbium, play a crucial role in manufacturing various technological products that are essential for low-carbon energy and transportation systems. Given the limited supply from in-ground REE mines, circular economy strategies have gained attention as potential solutions for supply chain issues. However, the specific impacts of these strategies on the global REE supply and demand landscape have been largely disregarded. 

A recent study, published in Nature Geoscience, presented an integrated model for exploring the complex linkages between REEs and climate pledges, and quantified the potential of circular economy strategies to reshape global supply chains of critical REEs. It was conducted by researchers from the Institute of Urban Environment of the Chinese Academy of Sciences, Peking University, Newcastle University, Leiden University, and other institutions.   

Based on their previous studies regarding REE sustainability, the researchers developed a novel model called the Dynamic Integrated Model of Rare Earth Circularity and Climate Target (DIRECCT) to analyze the effects of circular economy strategies on global REE supply and demand. The model considered both in-ground stocks and in-use stocks, as well as their dramatic actual and projected geographic shift across ten regions from 2001 to 2050 under three widely accepted climate scenarios.   

The researchers found a significant mismatch between in-ground stocks, supply, and demand at specific regional and element levels, highlighting that heavy REEs such as dysprosium and terbium would present an obstacle to achieving net-zero emission targets. In particular, the ongoing consumption of REE in low-carbon products can substantially reallocate REEs from producing regions to consuming regions. As in-ground stocks decline among mineral suppliers, the accumulation of in-use stocks in consuming regions can foster a more balanced global REE supply landscape.   

In addition, this study highlighted the crucial roles of various circular economy strategies, including reduction, substitution, reuse, and recycling, in reshaping global REE supply chains. The researchers found that the implementation of these strategies will lead to an increase in REE supply from urban mines within the next three decades, which will significantly reduce dependency on REE in-ground mines. Furthermore, some regions might also achieve a closed-loop REE supply with the implementation of these strategies.   

Through the integrated modelling of dynamic diffusion of in-use stocks from in-ground stocks, this study offers new insights into the geopolitical chessboard of critical raw materials and the potential impacts of circular economy strategies on REE regional disparities, geopolitical dynamics, and climate goals. Together, this information can serve as the scientific basis for international cooperation in promoting circular economy REE strategies for global low-carbon and just transitions.  

The roles of different circular economy strategies in the shift of in-ground minerals to in-use stocks for global low-carbon transition (Image by WANG Peng)