TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The conversion step is carried out by transesterification in the presence of basic catalyst. The process comprises filtration of the pressure oil before the conversion step. The separated ethylic ester from the glycerin is washed to eliminate the water-soluble impurities and dried under vacuum. Preferred Components: The ethanol is bioethanol. The glycerin and the ethylic esters are separated by decantation or centrifugation. The seed is rapeseeds. EXAMPLE - Cleaned oil producing seeds was pressed with a single-screw press to obtain a crude oil pressure with less than 2% of suspended materials, and a fatty oil cake containing 5-18% of oil compared to the dry matter. Then crude oil pressure was filtered to eliminate the suspended material. In parallel, the fatty oil cake was dried at 60-100degrees C in a drying oven or drier to obtain a dry oil cake with moisture percentage of lower than 2.5 wt.%. The contained in the dry oil cake was then extracted with anhydrous ethanol. The extraction was carried out in co-current or counter-current, at 50-70degrees C to obtain oil/ethanol mixture to obtain the ethylic ester and a thin oil cake, which was recovered the ethanol by vacuum moderate evaporation. The filtered oil pressure and oil/ethanol mixture from the fatty oil cake were mixed at 60-80degrees C in the presence of a basic catalyst e.g. sodium hydroxide and potassium hydroxide to obtain the ethylic ester and glycerin. Then transesterification reaction was carried out for 1-24 hours. After transesterification, the ethanol in excess was recovered by distillation under moderated vacuum. Then recovered ethanol was recycled. The evaporated ethanol in excess and the glycerin was separated from ethylic esters either by decantation, or by centrifugation. Then the recovered ethylic esters was finally washed with demineralized water to eliminate the traces of catalyst, soaps, glycerol and other water-soluble impurities, and then dried under vacuum to obtain the ethylic ester as biodiesel fuel used in the engines or be mixed with an oil fuel.