TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The liquid alkyl ester is further combined with additional alcohol to form a combined liquid alkyl ester stream. The combined liquid alkyl ester stream is flowed upward through transesterification reactor (18) between liquid glycerol outlet (II) and alkyl ester outlet (II). The biomass is reacted with additional alcohol to form additional liquid glycerol and alkyl ester stream (II). The additional liquid glycerol settles towards bottom of reactor (18). The alkyl ester stream (II) is removed from upper portion of reactor (II). The alkyl ester stream (II) is washed by introducing the alkyl ester stream (II) to near bottom of water wash vessel (28) and introducing water to near top of the water wash vessel, to form a washed alkyl ester stream. The washed alkyl ester stream is then dried. Preferred Composition: The combined liquid stream further comprises a transesterification catalyst (I). The combined liquid alkyl ester stream further comprises a transesterification catalyst (II). The amount of alcohol is less than or equal to 10% more than stoichiometric amount for conversion of biomass to liquid alkyl ester. The percent conversion of biomass to liquid alkyl ester is greater than or equal to 95 mass%, and less than or equal to 5 mass% of glycerol is removed from transesterification reactor (I) in liquid alkyl ester stream. Preferred Material: The biomass is fatty acid, triglyceride, natural oil comprising free fatty acid and/or natural fat comprising free fatty acid, preferably sunflower seed oil, soya bean oil, corn oil, cottonseed oil, almond oil, groundnut oil, palm oil, coconut oil, linseed oil, castor oil, rapeseed oil, industry tallow and/or abattoir waste. The biomass comprises used cooking oil. Preferred Compound: The alcohol is 1-4C alcohol, preferably methanol, ethanol, isopropanol, butanol and/or multivalent alcohol. Preferred Properties: The combined liquid stream has Reynold's number of less than or equal to 2100. The combined liquid stream flows upward through the reactor in a laminar flow.