The research and developments on the alternative fuels used in diesel engines are essential to decrease the exhaust emissions to meet the upcoming emission regulations such as EURO-VI. Among the renewable and alternative fuels, biodiesel is the most representative fuel since it is produced from biological feedstocks. In many countries, biodiesel is already being used in diesel engines because it does not require any modification on the fuel supply system [1]. Biodiesel can be produced from various feedstocks. The fuel properties of biodiesel can vary depending upon processing technology and feedstock, but they generally have high cetane number, oxygen content, near-zero sulfur content, and very low aromatic content when compared to conventional diesel fuel. The molecular structure of biodiesel is similar to diesel fuel and it contains additional oxygen (O2) which is useful to reduce HC, CO and soot in the exhaust. However, a diesel engine fueled with biodiesel or its blends generally release higher NOx emission than that of petroleum-based diesel fuel [2,3].