Energy- and exergy analysis of rape seed oil methyl ester (RME) productionunder Swedish conditions

In this study the rape seed oil methyl ester (RME) production chain was ana lysed with respect to its energy- and exergy efficiencies. The differences between results from an ordinary energy analysis and an exergy analysis of the production were also quantified and discussed. The sensitivity of the r esults to changes in some of the most important input parameters were then analysed in order to find production strategies that increase the exergy ef ficiency. The study was applied to rape seed cultivation situated in southe rn Sweden. The rape seed oil was hot pressed in a large-scale giant, and th e RME was esterfied in the same factory as that in which in the rape seed o il was pressed. Both direct and indirect energy and exergy flows used for R ME production were included. The analysis showed that a large part of the e nergy and exergy used to produce RME was related to nitrogen fertilizers an d diesel fuels. Another important conclusion was that the exergy efficiency of the production in general is higher than the energy efficiency. A third conclusion was that it is possible, by using alternative production strate gies, to improve the exergy efficiency without decreasing the energy effici ency. (C) 1999 Elsevier Science Ltd. All rights reserved.