Dynamic life cycle quantification of metallic elements and their circularity, efficiency, and leakages

The global consumption of metals is tremendously high and growing, a problem that calls for immediate action. This paper presents a comprehensive investigation on the anthropogenic use of 55 metallic elements in two main parts: life cycle quantification and assessment. Firstly, a dynamic life cycle model is constructed to quantify annual flows, losses, and stocks during their technical use periods, that is mainly from 1900 to 2013. The results show that the global demand for 55 metals has increased from 224 Mt/yr in 1953 to 1543 Mt/yr in 2013. Meanwhile, emerging applications have created a tremendous demand for 32 metals rarely used prior to the 1980s. Furthermore, the in-use stock of all metals, except Hg, has been increasing. The results further reveal many diverse patterns in the per capita trends of these metals (i.e. increasing (27 elements), saturating (25 elements) and decreasing (2 elements)). Based on the material flow results, this study confirms that metals are used in an extremely inefficient manner. This was found by studying three indicators (total resource efficiency, circularity, and total losses) which exist on the anthropogenic cycle level. This study not only helps to highlight the necessity of closing the loop, but also urges that more attention be paid to the leakages along the metal cycle due to the significant losses (e.g. for every unit of metal use, around 4 units have been lost on average). Furthermore, the losses at each life stage are also assessed for each metal. The anthropogenic use of metals needs to be more efficient and metal-specific solutions from the manufacturing industry are needed. (C) 2017 Elsevier Ltd. All rights reserved.