The processing and refining steps implemented by oil mills for the production of rapeseed and soy oils, intended for the production of Biodiesel, have an impact on the concentration of acylated steryl glycosides (ASG) and steryl glycosides (SG). These minor components – natural components of vegetable oils – are suspected to negatively influence the filterability of Biodiesel.

Rapeseed oil methyl ester (RME) is currently not suitable for diesel particulate filters. The boiling characteristic of RME is an additional problem that presumably limits its further usability in Euro VI engines. Currently, hydrogenated vegetable oil (HVO) is in the state of obtaining acceptance as alternative fuel in the German legislation and is in the focus of discussions world-wide. HVO has physical and chemical advantages versus RME. In case RME should continue to be an appropriate fuel its molecule structure must be designed - probably by means of plant breeding. It is important to lower the boiling line by achieving chain lengths between 12 and 16 carbon atoms and to have in mind the oxidation stability by focussing the number and the position of double bonds. Moreover, aspects of emissions and health effects must be kept in mind. Besides plant breeding, research should focus on highly efficient biotechnical transesterification, producing simultaneously shorter chain lengths. The phosphorus and metal contents of future biodiesel must become significantly lower than the specification limits that are valid at present.

Measurements of exhaust gas were carried out for a heavy-duty engine using four different fuels: biodiesel (B100); fossil diesel fuel; Shell V-Power® diesel fuel; and a blend of Aral Ultimate® diesel fuel with 5% biodiesel. The aim of the underlying research project – entitled “Measurement of ultra-fine particles in the exhaust gas of diesel engines fuelled with biodiesel”– was to examine in detail the increase in ultra-fine particles that is observed when biodiesel is used instead of fossil diesel fuel. An assessment of the risks of exposure to ultrafineparticles was expected as the outcome of the research.