Applying and advancing the economic resource scarcity potential (ESP) method for rare earth elements

Abstract

A number of studies have identified rare earth elements (REE) as critical metals due to their high economic importance combined with a high risk of supply disruption (Du and Graedel, 2011; Nassar et al., 2015; Schneider et al., 2014). The current methods used to calculate resource depletion in life cycle assessments (LCA) neglect socio-economic, regulatory and geopolitical aspects, nor do they include functionalities such as material recycling or reuse that control the supply of raw materials. These are important factors in determining criticality and are the controlling factors on REE availability rather than geological availability. The economic scarcity potential (ESP) method introduced by Schneider et al. (2014) provides a framework to calculate criticality. This paper reviews the ESP method and advances the method based on recent developments in material criticality. ESP criticality scores for 15 REE with the addition of Au, Cu, platinum-group metals (PGM), Fe and Li are measured. The results highlight that Nd and Dy are the most critical REE, owing mainly to the high demand growth forecast for these two elements. A pathway is presented for incorporating these calculated scores into the ReCiPe life cycle impact assessment (LCIA) method of a LCA.