Different pathways bear different outcomes: examining the environmental footprints migration of aluminum scrap trade

Aluminum scrap is a globally traded metal commodity. Its recycling and utilization are not only crucial for global aluminum resources security, but also the abatement of climate change impacts and environmental pollution caused by aluminum production. Taking the perspective of international trade, a comparative analysis of the life cycle environmental footprints (carbon, water, and energy) of aluminum scrap recycling is carried out, for different trade pathways. Herein China, Southeast Asia, the European Union and the United States are selected as the typical countries or regions for aluminum scrap trade, with 1 t of recycled aluminum ingots being the functional unit. The results show that the carbon footprint for Southeast Asia is relatively high, due to the underlying energy mix of grid. Among the different trade pathways, the alternative with comparatively lower levels of environmental footprints involves EU-based recycling followed by transporting to China, which yields the carbon footprint at a level of 500.86 kg, water footprint 24.65 m ^3 , and energy footprint 7612.42 MJ per ton. The US-China aluminum scrap trade pathways show similar trends. Compared with direct export and transit export, the environmental footprints are markedly reduced if recycling takes place in the exporting regions such as the EU or the US, due to relatively higher recycling efficiency and reduction in weight transported.