Methods for improving the cold flow properties of biodiesel with high saturated fatty acids content: A review

The scarcity of fossil fuels in medium and long term has led to several researchers to propose different alternatives to replace them, where the biodiesel had been proposed as the main replacement of conventional diesel oil. The main technical problem of this fuel is that doesn't have an adequate behavior in cold environments whereby several alternatives has been proposed for improve biodiesel cold flow properties. Biodiesel made from oilseeds with high contents of saturated fatty acids like palm oil shown higher oxidation stability and high heating value but they have cold flow properties worse than other biodiesels due to solidification of the fatty acids at high temperatures. Due to this behavior, among alternatives for improve cold flow properties in the biodiesel can be finding mixture's oils with a high content of unsaturated fatty acids, oil fractionation, Alkyl esters structure modification and additive use. The option selected must be studied in detail, due to variability of the biodiesel composition and all options can involve complications. It was observed throughout the review that some of them can improve cold flow properties up to 20 degrees C, but their effect on this kind of biodiesel has to be evaluated in detail.