A crustal scarcity indicator for long-term global elemental resource assessment in LCA

Abstract

Purpose How to assess impacts of mineral resources is much discussed in life cycle assessment (LCA). We see a need for, and a lack of, a mineral resource impact assessment method that captures the perspective of long-term global scarcity of elements. Method A midpoint-level mineral resource impact assessment method matching this perspective is proposed, called the crustal scarcity indicator (CSI), with characterization factors called crustal scarcity potentials (CSPs) measured as kg silicon equivalents per kg element. They are based on crustal concentrations, which have been suggested to correlate with several important resource metrics (reserves, reserve base, reserves plus cumulative production, and ore deposits), thereby constituting proxies for long-term global elemental scarcity. Results and discussion Ready-to-use CSPs are provided for 76 elements, through which the CSI can be calculated by multiplying with the respective masses of elements extracted from Earth's crust for a certain product. As follows from their crustal concentrations, the three platinum-group metals iridium, osmium, and rhodium have the highest CSPs, whereas silicon, aluminum, and iron have the lowest CSPs. Conclusion An evaluation of the CSPs and the characterization factors of four other mineral resource impact assessment methods in LCA (the abiotic depletion, the surplus ore, the cumulative exergy demand, and the EPS methods) were conducted. It showed that the CSPs are temporally reliable, calculated in a consistent way, and have a high coverage of elements in comparison. Furthermore, a quantitative comparison with the characterization factors of the four other methods showed that the CSPs reflect long-term global elemental scarcity comparatively well while requiring a minimum of assumptions and input parameters. Recommendations We recommend using the CSI for assessments of long-term global elemental scarcity in LCA. Since the CSI is at the midpoint level, it can be complemented by other mineral resource impact assessment methods (both existing and to be developed) to provide a more comprehensive view of mineral resource impacts in an LCA.

Rock-to-Metal Ratio: A Foundational Metric for Understanding Mine Wastes

“…The RMR is also not equivalent to the crustal scarcity indicator, 49 the surplus ore method, 50 or other similar methods 51 that assume a cumulative relationship between grade and tonnage extracted. Resource depletion indicators require assumptions about the likelihood of future mineral resource discoveries, the quantities of undiscovered in situ resources, and the development of extraction technology.…”

Method to incorporate green chemistry principles in early-stage product design for sustainability: case studies with personal care products

“…from ores that are less rich). This results in relatively high CF values for some minerals that are abundant in the earth's crust (e.g., silicon), yielding LCA outcomes that some practitioners have rejected as unrealistic, so Arvidsson et al developed a mineral resource indicator, Crustal Scarcity Potentials (CSPs), that attempts to correct this concern, 34 which we adopted as the PI-indicator. The CSPs are normalized to silicon which has an assigned abundance of one, with higher CSP values denoting lower abundance.…”

Life-cycle impact assessment methods for physical energy scarcity: considerations and suggestions

“…This is redundant, introduces a risk of double counting, and creates interdependency between the CF and the inventory data because q is typically a subset of the global extraction. 8 In addition, as pointed out by Arvidsson et al (2020), technospheric parameters generally change faster than parameters describing the natural system and thus the CFs will need more frequent updating if technospheric parameters are included. While this can be resolved through frequent updating, it constitutes a practical challenge and brings a risk that the CFs become outdated.…”

“…1.1, however, existing life cycle impact assessment (LCIA) methods rarely consider the potential scarcity of different energy resource types, i.e., how the availability of an energy resource type might limit its use in society. Larger efforts Communicated by Matthias Finkbeiner have been put into assessing scarcity-related impacts of other resource types in LCA, such as mineral/elemental resources (Cimprich et al 2019;Hélias and Heijungs 2019;Arvidsson et al 2020;van Oers et al 2020) and biotic resources (Crenna et al 2018;Hélias et al 2018;Odppes et al 2021). Since the availability of different energy resource types has been critical for human development and well-being throughout history (Ponting 2007), we suggest that energy scarcity also deserves further elaboration.…”

“…This is similar to the selection of silicon as reference resource for the mineral resource LCIA method called the crustal scarcity indicator (CSI), which was done since silicon is the most abundant element in the Earth's crust(Arvidsson et al 2020). …”