ABSTRACT
Biodiesel is composed of monoalkyl esters of long-chain fatty acids derived from renewable sources such as vegetable oils or animal fats (Ma and Hanna, 1999; Fukuda et al., 2001; Knothe, 2005; Knothe and Dunn, 2005; Moser, 2011). It can be used as an alternative fuel to petroleum diesel fuel. The advantages of the use of biodiesel over petroleum diesel fuel include lower overall exhaust emissions (Knothe and Dunn, 2005; Reaney et al., 2005; Knothe, 2010), superior lubricity and ash point (Reaney et al., 2005), renewability, low toxicity and biodegradability (Knothe, 2010). In addition, it is miscible in petroleum diesel fuel in all proportion and can be used in diesel engine with no engine modication required as pure or blended with petroleum diesel fuel (Knothe, 2005). The disadvantages of biodiesel include high feedstock cost, lower heating values, inferior low-temperature operatability and oxidative stability, and in some cases, higher NOx exhaust emissions (Knothe, 2010; Moser, 2011).
