Characterization of raw materials based on supply risk indicators for Europe

Purpose: The concept of “resource criticality” has recently emerged as a policy priority and research subject, usually referred to the risk of supply disruption for mineral resources, due to economic and geopolitical reasons. Different methodologies for assessing critical raw materials (CRM) have been developed in governmental and research contexts, and the possibility of including the resource security aspect in life cycle assessment (LCA) has been claimed by different authors. The present paper aims at integrating CRM considerations in LCA in order to address socio-economic and strategic aspects related to resource use. Methods: In this paper, we first explore how resource criticality could be interpreted, taking into account a wider perspective and a multidimensional concept. This includes the consideration of environmental and depletion aspects, in addition to the dominant interpretation, based on economic and geopolitical considerations. We then focus on the economic dimension of the resource criticality and propose the integration of this aspect in LCA through the use of characterization factors (CFs) based on the supply risk factors for Europe. Four different methodological options for resource security CFs are tested in the impact assessment of 50 processes and products. These options include the following: supply risk factors as such; two exponential functions of the supply risk factors, aimed at increasing the variability of the dataset, and the ratio between supply risk and production data, which reflect the size of the market, giving more importance to the materials used in small amounts in products and applications (like, e.g. specialty metals, that are often perceived as critical). Results and discussion: The results show how the impact depends on the supply risk factors or on the mass depending on the algorithm used. Even if there is no objective way to establish how much importance should be given to one aspect or the other, we conclude that the use of the factors “supply risk/production” results might better reflect CRM importance and therefore could be used in LCA for an assessment of resource security impact for EU. Applying an exponent to the supply risk factors, the values are spread on a wider range and it is possible to spot the CRM among the resources within an inventory. Conclusions: The choice of the indicator is based rather on how important is the need of identifying a CRM in the inventory, e.g. in order to optimize CRM use, explore substitution options and enhance recovery in waste management.