Re-refining of Lubricant Oil Used and Contaminated (LOUC) or its combustion in cement plants? An exploratory study in Brazil based on the life cycle assessment and circularity indicators

Abstract

Brazil is the sixth largest global lubricants market, and the sixth largest generator of Lubricant Oil Used and Contaminated (LOUC). No studies have been found to date coupling Life Cycle Assessment (LCA) and Material Circularity Indicator (MCI) to evaluate two end-of-life LOUC scenarios: (1) combustion for the co-generation of thermal energy in cement kilns; and (2) re-refining for the production of base oil. Thus, this paper compared the environmental performance via LCA and MCI of these two end-of-life strategies in Brazil. Ten LCA environmental impact categories were selected according to the ReCiPe 2016 (H) midpoint method, and the MCI was calculated using the Ellen MacArthur Foundation methodology. The results showed a more favorable circularity (up to 41.1 %) and less environmental life cycle impacts of LOUC re-refining (up to 99 % less impacts). However, when analyzing energy demand in the cement industry, the LOUC supply proves to be an environmentally viable alternative for the partial or total replacement of coke consumption. As a conclusion, combustion of LOUC presents an environmentally viable solution compared with coke input in clinker production, but a worse solution if compared with a re-refining strategy.