Evaluation on biodiesel cold flow properties, oxidative stability and enhancement strategies: A review

Poor cold flow properties of biodiesel especially those that are composed mainly of saturated fatty acids is one of the major drawbacks faced by most biodiesel manufacturers. During winter or cold weather, the biodiesel tend to solidify which clogs fuel lines, filters and injectors that lead to engine operability problems. As it limits biodiesel marketability, it is desirable to improve these properties. Literatures have shown that there are numerous ways that can be used. However, lack of review papers in this area especially on the fundamentals aspects of biodiesel properties makes it difficult to choose the best and suitable improvement method that is compatible with the biodiesel type itself. This paper therefore aims to provide a comprehensive review on this area which covers relevant topics such as (a) biodiesel compositions, (b) cold flow properties (e.g. pour point, cloud point, cold filter plugging point), (c) mechanisms, factors affecting and impact of the cold flow properties, (d) oxidative stability, (e) methods to improve the cold flow properties, (f) methods to improve biodiesel oxidative stability and et cetera. This information is hoped to give deeper understanding on the fundamentals and new perspectives towards the production line to produce desirable quality of biodiesel that is marketable around the globe.