Trends in Japanese households' critical-metals material footprints
This study adopts the concept of material footprint (MF), an indicator for consumption-based material extraction via international trade, and identifies the relationship between the MFs of critical metals for low-carbon technologies – neodymium, cobalt, and platinum – and Japanese household consumption through a multiregional input–output approach using the global link input–output model. We focus solely on the impact of changes in consumption patterns caused by demographic change on the structures of the MFs from 2005 to 2035. As a result, the total MFs of neodymium, cobalt, and platinum in 2035 are estimated to be 11%, 6.6% and 4.7% lower than in 2005, respectively. In terms of commodity sectors, the MFs of the three metals induced by “passenger motor cars” are estimated to decrease most between 2005 and 2035. Finally, we carried out an assessment of the extent to which the products dealt with under current Japanese recycling laws cover the MFs calculated for 2035. This indicates that continued enforcement of the recycling laws can play an important role in alerting consumers to the MFs of critical metals, particularly neodymium. For improving the accuracy of the above estimates, further studies need to incorporate other future trends like technologies and trade.