Global flows of critical metals necessary for low-carbon technologies: The case of neodymium, cobalt, and platinum

Keisuke Nansai, Kenichi Nakajima, Shigemi Kagawa, Yasushi Kondo, Sangwon Suh, Yosuke Shigetomi, Yuko Oshita

Research output: Contribution to journalArticlepeer-review

148 Citations (Scopus)


This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

Original languageEnglish
Pages (from-to)1391-1400
Number of pages10
JournalEnvironmental Science and Technology
Issue number3
Publication statusPublished - Feb 4 2014

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


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