Methodologies for modification of characteristics of biodiesel for wider acceptability as diesel engine fuel

The internal combustion (IC) engine has proved to be the pivotal technology to meet the transportation needs of ever-increasing populations. IC engine technology and its future are mainly dependent on fuel sources for which the demand is continuously rising worldwide. One such fuel that has the potential to replace diesel (fossil) fuel for IC engines is biodiesel. Its inherent characteristics such as renewability, biodegradability, enhanced lubricity, cetane number, abundance in feedstock, availability at local level, and better emission profile provide easy acceptability of biodiesel. However, their suitability is hindered by a few shortcomings, including inferior oxidative stability, poor cold flow properties, high viscosity, lower volatility, unsaturated fatty acid esters, water absorbency, and lower heat of combustion. These alternative fuels are less efficient if they are utilized directly as fuel in diesel engines. Therefore their characteristics must be appropriately modified by varying the properties that are pertinent to maximum engine power and thermal efficiencies with reduced fuel consumption and reduced engine tail pipe emissions. This chapter discusses the efforts of different researchers and their suggested methodologies in modifying biodiesel fuel characteristics. This work will also pave the way toward wider acceptability of biodiesel fuel.