Evaluating Critical Raw Materials in the energy sector through an energy criticality index

The deployment of clean energy technologies to meet global decarbonization targets is driving an increase in the demand for Critical Raw Materials: for the energy sector alone, reaching net-zero emissions by 2050 requires up to a sixfold increase of these materials. Despite the growing need of evaluating material criticality of energy technologies, existing methods also based on life cycle thinking approach currently lacks a universally accepted framework that considers different aspects of “criticality.” To address this gap, the study proposes the Energy Criticality Index (ECI), a novel index developed within the Life Cycle Assessment (LCA) framework designed particularly for the energy sector. ECI integrates supply risk, economic importance, geological reserves, import reliance and recyclability into a single dimensionless parameter. To demonstrate its applicability, two hydrogen energy technologies at different stages of technological maturity are tested: a lab-scale alkaline electrolyser cell and an industrial-scale proton exchange membrane (PEM) fuel cell. The application to the two case studies shows that the ECI redistributes criticality: for the alkaline electrolyser, fluorspar (39%) and gallium (20%) emerge as primary hotspots, replacing the rare earth elements dominated profile (92%) of the SH2E (Sustainability assessment of Harmonized Hydrogen Energy systems) method, a criticality index used as benchmark for the same case study. For the fuel cell, gallium (44%) and tantalum (33%) are identified as dominant contributors despite their negligible mass. The index advances the state of the art by substituting annual consumption with geological reserves, introducing a vector magnitude formulation, combining supply risk and normalised economic importance. The same approach is replicable across different technologies for which a life cycle inventory is available.