Sunflower (Helianthus annuus L.), a member of the Compositea family, is an important oilseed crop worldwide (Fig. 4.2), yielding approximately 45-50% oil and the quality depending on the region (Pereyra-Irujo et al., 2009). The feasibility of sunflower oil used as a raw material for biodiesel production has been extensively researched in Spain, including homogeneous and heterogeneous catalysts (Vicente et al., 1998, 2004, 2005; Antolin et al., 2002; Arzamendi et al., 2006, 2008; Ramos et al., 2008). Auxiliary energies, such as low frequency ultrasonication, have been proposed to enhance the reaction yield in transesterification reactions using ethanol (Georgogianni et al., 2008).

Diesel engine tests have also been performed showing a power loss up to 10% when the engine was run on biodiesel (Kaplan et al., 2006). However, the use of blends with diesel fuel up to 30% biodiesel reported no significant changes in BSFC (Neto da Silva et al., 2003). CO2, CO and NOx emissions seem to be lower than those of diesel fuel (Ilkilic, 2008). The use of straight sunflower oil in

an indirect injection diesel engine also exhibits exhaust emissions reduction and no negative effects on the engine performance (Canakci et al, 2009).