Biodiesel is an energy source that is comparable to standard diesel fuel. In contrast to conventional diesel fuel, however, it is not obtained from fossil oil, which everyone knows is a resource that is only available in limited amounts and is too valuable simply to be burned. Biodiesel is manufactured from such biogenic raw materials as vegetable oil that are therefore renewable. The field crop rapeseed is the most important raw material source of this kind of biodiesel. Since the raw materials used to manufacture it are renewable, biodiesel is counted as a renewable energy source. Chemically speaking, biodiesel is rapeseed methyl ester (RME). RME is created by the transesterification of fats and oils (triglycerides) with methanol. In the course of the acid- or base-catalysed reaction, the trivalent alcohol glycerine is replaced by methanol, in order to improve the flow properties of the fuel and to prevent it freezing even at very low temperatures. In addition to RME, i.e. biodiesel, a by-product of the reaction is raw glycerine, which collects as a residue because of its higher specific density; one hundred kilograms of glycerine are produced per tonne of biodiesel. Raw glycerine contains not only glycerine but also such substances as water, excess methanol and free fatty acids.