Reinventing exergy as indicator for resource depletion impacts in LCA

While resource aspects are gaining increasing importance for the sustainability assessment of new technologies, the question of how to assess the depletion of abiotic resources is still controversially discussed. Different methodologies exist for their quantification within life cycle assessment (LCA). Among them, thermodynamic approaches have the advantage of considering aspects of absolute quantity (reserves or amount of a substance contained in total in earth’s crust) and of quality (concentration of the target element in the mined resource), making them a potentially appealing approach for assessing resource depletion. However, existing approaches are either far from the original thermodynamic idea of exergy or far too complex and not applicable for resource accounting. This work briefly discusses the suitability of exergy-based approaches for resource assessment, and then suggests a simple but comprehensive methodology for quantifying resource depletion related with the concept of chemical concentration exergy (MDP^ces). It provides a calculation approach for quantifying the MDP^ces and estimates the corresponding values for some representative key metals.