LCA of petroleum-based lubricants: state of art and inclusion of additives

Abstract

While the application of Life Cycle Assessment (LCA) to lubricants can be considered fully operational for general purposes outside the lubricants industry, where Life Cycle Inventories (LCIs) of mineral and synthetic base oils can be used interchangeably and where additives can be excluded, this is not the case for research and development purposes within the industry. Previous LCAs of base oils are not sufficiently detailed and comprehensive for R&D purposes, and there are no LCAs of lube additives and fully formulated lubricants. The aim of this paper is to integrate and expand previous LCAs of base oils and to investigate on the contribution of lube additives to the environmental impacts of a fully formulated lubricant. This study considers three base oils (mineral, poly-alpha-olefins (PAO) and hydrocracked) and a set of lubricating additives typically used in fully formulated engine oil. The LCA model is based on both industry and literature data. Trends in the lubricants industry towards more sophisticated base oils correspond to remarkably higher environmental impacts per kilogram of product but lead to reduced impacts per kilometre. The contribution of additives to the life cycle impacts of commercial lube oil was found to be remarkably high for some impact categories (nearly 35 % for global warming). As base oil is concerned, this study made the point on data availability and provided a contribution in order to integrate and expand previous LCAs of mineral base oil and PAO. On the side of additives, the main conclusion is that in modern lubricants, the contribution of additives in terms of environmental impact can be remarkably high and, therefore, they should not be excluded.