Life Cycle Inventory (LCI) Stochastic Approach Used for Rare Earth Elements (REEs), Considering Uncertainty

The purpose of the paper is to present the results of the stochastic modelling with uncertaintyperformed with the use of Monte Carlo (MC) simulation with 10,000 cycles and a confidence interval of95 %, as recommended. Analysed REEs were fitted by lognormal distributions by using the Crystal Ball®(CB) spreadsheet-based software after defining the geometric mean value (μg) and the standard deviation(σg), automatically calculated (matches) the lower, as well as, upper boundaries of lognormal distribution.The number of replications of a simulation affects the quality of the results. The principal output reportprovided by CB and presented in this study consists of the graphical representation in the form of thefrequency chart, percentiles summary, and statistics summary. Additional CB options provide a sensitivityanalysis with tornado diagrams. The data that was used for MC simulation of the LCI model includesavailable and published data concerning associated with the REEs. This paper discusses the results andshow that the adopted approach is applicable for any REEs used in the LCI studies under uncertainty. Theresults obtained from this study can be used as the first step in performing a full LCA analysis and helppractitioners as well as decision-makers in the environmental engineering and management.