NOVELTY - Production of alkyl esters of fatty acids involves direct esterification with glycerol of fatty acid substances with neutralisation number 2-300; neutralisation with alkali of organic and inorganic acids; transesterification with alcohols; and distillation of the resulting esters to give biodiesel according to regulations, where the distillation takes place by a thin layer or molecular evaporator, with absolute distillation pressure of 0-4 bar at 150-200degreesC.    USE - For production of alkyl ester of fatty acids use as biodiesel (claimed).    ADVANTAGE - The process is simple and convenient for producing biodiesel which gives a good yield and uses raw materials of plant and/or animal origin. The biodiesel has a very low sulfur content (less than 0.001%) and so it does not contribute to the phenomenon of acid rains; it reduces dust emissions up to 50% and is compatible with the catalyst; does not contain benzol or other cancerogenous components; has a high flash point (greater than 1, 100degreesC); not classified as a dangerous material and so it is easy and safe to handle; it is highly biodegradable (99.6% after 21 days) and does not pollute the soil or the water if accidentally spilled; has a high lubricating power and decreases engine wear; has a closed CO2 cycle and so its combustion in the engine produces an emission of CO2 in the same quantity as that absorbed by plants from the air in their growth process. The biodiesel is an excellent fuel for self-igniting engines due to this most vehicle manufacturers (cars, trucks, including the manufacturers of diesel engines) have granted permission to use biodiesel in their products. The biodiesel may be mixed with traditional diesel fuel, in any percentage, improving its performance. In winter, as with traditional diesel fuel, it is enriched with additives, so that the driving conditions remain absolutely unchanged in sub-zero temperatures; biodiesel can be kept without problems for a period of at least 12 months. The emission values of an engine fed with biodiesel are reduced in comparison with running on traditional diesel fuel. The use of biodiesel in the engine does not cause a fall in performance. The process contemplates the esterification of the acidity present in the fatty substances by means of glycerine with the exclusion of methanol, ethanol, propanol, butanol and other alcohols; excludes rectifying to eliminate condensation water due to the combination of alcohol and acid in the synthesis process; does not require purifications of the initial fatty substance; allows considerable energy saving.