Títol del pre-print: Global warming potential of the circular economy of aluminium: the role of old scrap recycling

For decades, aluminium recycling was a regional concern traditionally concentrated in the regions with high aluminium demand and a well-organized aluminium recycling industry. Today, however, aluminium scrap is a global raw material commodity. This change has increased the need to analyze the flows of aluminium scrap, as well as to determine the environmental consequences from aluminium recycling. The objective of this work is to determine the environmental consequences of the old scrap aluminium collection for recycling, considering the market interactions. The study focused on Spain as a representative country for Europe. We integrate material flow analysis (MFA) with consequential life cycle assessment (CLCA) in order to determine the most likely destination for the old scrap and the most likely corresponding process affected. Based on this analysis, it is possible to project some scenarios and to quantify the environmental impacts (generated and avoided) associated with aluminium recycling within a global market. From the MFA results, we projected that the demand for aluminium products will be met mainly with an increase in primary aluminium imports, and the excess of old scrap not used in Spain will be exported in future years, mainly to Asia. Depending on the marginal source of primary aluminium considered, the greenhouse gases (GHG) emission estimates varied between -17,088 kg of CO2 eq. t-1 of old scrap collected to -10,305 of CO2 eq. t-1 of old scrap collected for the global or local scenario, respectively. More GHG emissions are avoided with an increase in export flows, but the export of old scrap should be considered as the loss of a key resource, and in the long term, it will also affect the semifinished products industry. Mapping the flows of raw materials and waste, as well as quantifying the environmental impacts derived from recycling, has become an essential prerequisite to consistent development from a linear towards a circular economy.