TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The solid acid catalyst is present in an amount of 100-3000 g/liter of internal reactor volume; and comprises an inorganic solid acid or sulfated zirconia (preferably sulfated zirconia catalyst).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The feed comprises free fatty acid ( greater than or equal to 5, preferably greater than or equal to 10, especially greater than or equal to 20 wt.%). The feed comprises corn oil, soybean oil, cuphea oil, peanut oil, radish oil, rice bran oil, rapeseed oil, olive oil, cottonseed oil, sunflower oil, sesame oil, safflower oil, mustard oil, palm oil, coconut oil, jatropha oil, linseed oil, caster oil, evening primrose oil, borage oil, carboseed oil, false flax oil, hemp oil, ramtil oil, tung oil, copaiba oil, hong oil, colza oil, milk bush oil, petroleum nut oil, algal oil, fish oil, lard, tallow, yellow grease, brown grease, waste oil products, acidulated soap stock, meat rendering waste oil and/or recycled cooking oil. The alcohol comprises butanol, propanol, ethanol, methanol and/or their derivatives. Preferred Method: The obtained effluent comprises alkyl ester ( greater than or equal to 80, preferably greater than or equal to 83 wt.%) and glyceride ( less than or equal to 5, preferably less than or equal to 2, especially less than or equal to 1 wt.%). The excess solvent and/or water is present in the effluent, and the effluent composition excluding the excess solvent and/or water, comprises alkyl ester ( greater than or equal to 80, preferably greater than or equal to 83 wt.%) and glyceride ( less than or equal to 5, preferably less than or equal to 2, especially less than or equal to 1 wt.%). The effluent comprises free fatty acid (less than 15, preferably less than 10 wt.%). The effluent comprise less than 10 wt.% of glycerol. The reaction temperature and pressure are 100-220 (preferably 150-200, 145-175, 175-200 or 150) degrees C, and 75-200 psia, respectively. The reaction is carried out in the presence of ketone co-solvent, where the ketone comprises 2-butanone. The method additionally involves removing all or a portion of water present in the effluent to provide dried effluent; contacting an alcohol, the dried effluent, and solid acid catalyst in second reactor; and recovering from the second reactor, second effluent comprising free fatty acid ( less than or equal to 2 wt.%) and glyceride ( less than or equal to 2 wt.%), where the reaction temperature is 80-150 (preferably 100-120) degrees C.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The solid acid catalyst comprises at least one compound selected from polymeric ion-exchange resin, fluorinated polymer resin with sulfonic acid sites, nanostructured polymer catalyst and/or an inorganic acid catalyst; or nanostructured polymer catalyst (preferably nanostructured polymer catalyst). EXAMPLE - No suitable example given.