Correlation between physicochemical properties and quality of biodiesel

Biodiesel produced from renewable feedstocks represents a sustainable source of energy and will therefore play a significant role in providing the energy requirements for transportation in the near future. Biodiesel offers many benefits over conventional petroleum fuels, including the wide regional distribution of biomass feedstocks, high greenhouse gas reduction potential, biodegradability and a significant contribution to sustainability. Chemically, all biodiesels are fatty acid methyl esters (FAME), produced from raw vegetable oil and animal fat. However, clear differences in chemical structure are apparent when comparing one feedstock to the next in terms of chain length, degree of unsaturation and number of double bonds—all of which determine the fuel properties and quality of biodiesel as a diesel engine fuel. In this chapter, biodiesel feedstocks, production processes, chemical compositions, standards, physicochemical properties and in-use performance are discussed. A correlation study between the properties of biodiesel and its chemical composition is analysed using principal component analysis (PCA). The necessary data regarding the chemical composition and fuel properties of biodiesel were obtained from more than 100 papers published in recognised international journals. The PCA indicated that individual biodiesel properties have a complex correlation with the parameters of chemical composition. The average chain length and average number of double bonds are the most influential parameters that affect all biodiesel properties. The results of this analysis are presented graphically and discussed in this chapter. Therefore, this chapter will provide the reader a clearer understanding of the physicochemical properties of biodiesel