Notes on life-cycle assessments of vegetable oils

Renewable resources like vegetable oils constitute a central element in the discussion of the implementation of a sustainable development. Vegetable oils play an increasingly important part in the production of biodegradable materials. But considering the ecological effects of their production and use vegetable oils show advantages and disadvantages. Life-cycle assessments (LCAs) allow a detailed evaluation of their ecological performance. Carrying out LCAs the determination of the methodological proceedings is required. It is one of the objectives of the present study to ascertain if, or how strong, these methodological determinations can influence the results of LCAs. The LCA of refined rapeseed oil serves as an example. The following issues are of special interest here: the selection of a reference system, the balancing principles for coproducts, and the balancing principles for emissions under consideration of their site-specific impacts. Furthermore, the results for rapeseed oil and soybean oil are compared in order to find out if LCAs for different vegetable oils show similar results (which would allow the undiscriminate transfer of the LCA results from one oil to another). Finally, the LCA results of rapeseed oil, that have been obtained for the currently quantifiable parameters, are presented. As the study shows, the methodological approach can influence the LCA results significantly. Therefore, it is necessary to define and document the applied methodological approach carefully in order to base the LCA on verifiable facts and to obtain realistic results. The undiscriminate transfer of LCA results from one vegetable oil to another is not allowed because incorrect results are possible.