TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The acid catalyst is sulfuric acid, hydrochloric acid or sulfonic acid; and the alkali catalyst is sodium hydroxide, sodium methoxide or potassium hydroxide. The porous membrane comprises sintered carbon, carbon graphite, ceramic, titanium oxide, aluminum, Teflon (RTM: tetrafluoroethylene) or stainless steel.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Apparatus: The apparatus further comprises a reaction mixture pump; a permeate pump; a reaction mixture temperature regulator; and a washing unit. The reaction mixture pump pumps the reaction mixture stream to the reaction mixture side of the porous membrane. The permeate pump pumps the permeate away for further processing. The washing unit washes the permeate to facilitate phase separation of the glycerol into glycerol phase. The pores in the porous membrane have a size of 1 nm - 3 microns. The additionally comprises a permeate separation unit for separating the permeate into a fuel-rich fraction, an alcohol-rich fraction, and optionally a glycerol-rich fraction. The apparatus further comprises a reservoir for containing or temporarily holding a volume of at least one component of the reaction mixture in a location remote from the porous membrane, for example in a continuous loop of the apparatus.Preferred Process: The reaction mixture is kept under a positive pressure relative to the permeate, to facilitate the passage of fuel or fuel additive through pores in the porous membrane. The permeate is kept under a negative pressure relative to reaction mixture, to facilitate passage of fuel or fuel additive through pores in the porous membrane. The apparatus allows for batch production, semi-continuous or continuous production of the fuel or fuel additive. In this process, the reaction mixture is supplied to a reaction mixture side of the porous membrane via a reaction mixture stream; and the permeate is drawn away from the permeate side of the porous membrane by a permeate stream. The oil and alcohol are separately supplied to the reaction mixture stream. The oil and alcohol are pre-mixed prior to entry into the reaction mixture stream. The reaction mixture pump causes turbulence in the reaction mixture stream, and generates shearing forces to assist in oil droplet break-up and generation of the oil-in-alcohol emulsion. The alcohol in the permeate and the catalyst is recycled back to the reaction mixture stream. The catalyst is miscible with the alcohol. The temperature of the reaction mixture is regulated to at least 15 (preferably at least 60, especially less than 150)degreesC. The oil is heated either before or after entry into the reaction mixture to improve flowability, and optionally reduce heat-exchanger requirements in a reactor loop. The apparatus further comprises units to isolate the fuel or fuel additive from other components of the permeate. The pressure of the reaction mixture on a reaction mixture side of the porous membrane is at least 3 (preferably less than 7000) kPa, higher than a pressure of the permeate on a permeate side of the porous membrane. The pressure of the reaction mixture on a reaction mixture side of the porous membrane and a pressure of the permeate is less than 70000 kPa, higher than ambient pressure. The process further involves isolating or substantially isolating the fuel or fuel additive from other component of the permeate. The permeate comprising glycerol is further cooled to facilitate phase separation of the glycerol into a glycerol phase. The alcohol-rich fraction from the permeate separation unit is recycled to the reaction mixture stream. Transesterification of the triglycerides in the reaction mixture generates fatty acid alkyl esters (FAAE) as the fuel or fuel additive.Preferred Components: The oil comprises at least one lipid feedstock selected from virgin vegetable oils, vegetable oils, animal fats, palm oil, non-edible oils or waste frying oils. The permeate comprises glycerol. The catalyst is a transesterification catalyst, and the oil includes triglycerides. The catalyst is a solid catalyst, an enzyme catalyst, an acid catalyst (0.5-6 wt.%) or an alkali catalyst (0.1-6 wt.%). The alcohol is methanol, ethanol, propanol or 1-butanol.