Comparison of rapeseed and mineral oils using Life-Cycle Assessment and Cost-Benefit Analysis : Lipochimie et développement durable

A combination of Life-Cycle Assessment (LCA) and Cost-Benefit Analysis (CBA) was used to evaluate and compare the relative environmental impacts and socio-economic costs of several products, made from either rapeseed oil or mineral oil in the UK. The chainsaw bar oil case study is used to demonstrate the methodologies used and results obtained. Chainsaw bar oil is a total-loss oil, and has considerable potential for substitution of the conventional base oil (mineral oil) with rapeseed oil. Results are presented from LCA impact assessments of the mineral oil and rapeseed oil chainsaw lubricants. Several scenarios were compared using different co-product allocation and alternative land-use assumptions. Global warming potential (GWP) impacts were lower for rapeseed chainsaw oil, in all scenarios, than for the mineral oil product. Other environmental impacts illustrated that both assumptions (i.e. whether to examine the total or marginal impacts) and allocation can strongly influence conclusions. The most realistic scenario for rapeseed oil was considered to be 70% allocation of burdens to the oil, with winter wheat impacts subtracted from those of oilseed rape. With this scenario, all environmental impacts considered for chainsaw lubricants were lower for rapeseed oil. Monetary valuation of impacts through CBA varied, depending on the valuation system used, but in general rapeseed oil chainsaw lubricant had lower costs than the mineral oil product. Allocating some of the environmental burdens of crop production and crushing to rapeseed meal, and consideration of marginal impacts relative to alternative land uses increased the apparent environmental benefits of rapeseed oil chainsaw lubricant. Combination of LCA and CBA will require further development but affords new opportunities for socio-economic interpretation of environmental aspects.