LCA OF RME VERSUS DIESEL OIL - THE PRESENT STATE OF DISCUSSION

In the beginning of the nineties the first LCAs on ''RME versus diesel oil'' only balanced energy and CO2. In the meantime numerous studies concerning this topic have been published. The methodology has been sc rutinized and improved, comprehensive LCAs have been completed, and th e first evaluation modells have been developed. Based on this solid kn owledge an assessment of the ecological advantages and disadvantages o f RME as a substitute for diesel oil is possible. This final assessmen t of the parameters includes a comparison of their ''specific contribu tions'' followed by a verbal, i.e. non-quantitative evaluation that dr aws on their ''ecological relevance''. ''Resource demand'' and ''green house effect'' - two environmental impact categories of high to very h igh ecological importance - are unequivocally in favour of RME. Under certain circumstances this is also valid for the local emissions of di esel particulates as third category. On the contrary, diesel oil obtai ns better results only in several categories of medium and in one cate gory of high to very high ''ecological relevance'', that is in the cat egory ''stratospheric ozone depletion''. But problems to interprete th e available data lead to uncertainties concerning the general assessme nt of the ''specific contribution'' of N2O to the stratospheric ozone depletion. An overall final assessment in favour of RME can be justifi ed. However this assessment is not inescapable. In particular when a p recautionary environmental approach is preferred the above argumentati on can be reversed as long as there is interpretational ambiguity conc erning N2O. Finally, it is necessary to mention that all evaluation mo dells - including the present - cannot a priori be completely scientif ically objective. The modells may produce different results if used at other times and or by other users. This fact stringently requires the documentation of the complete evaluation process in order to allow a review. The results cannot be generalized unrestrictedly. In the prese nt case study different processes of rape seed production, provision a nd use, or the development of optimized motor engines for the use of R ME can lead to different assessments. Therefore, any final assessment has to consider explicitely the system boundaries. Additionally, asses sments of individual ecological objectives are possible, e.g. if a wat er protection area is to be protected by the use of RME instead of die sel oil.