This study focuses on biodiesel production from residues in particular tallow and used cooking oil (UCO). Ireland has 8% of the EU cattle herd with less than 1% of the EU population. Thus a significant quantity of slaughter residues is available for energy production. The total energy potential associated with slaughter wastes and UCO is estimated to be 7.07 PJ/a; 61% of which is suitable for biodiesel production. The potential quantity of biodiesel is equivalent to 2.1% of predicted transport fuel use in 2010; three quarters of the 2010 biofuels target. Biodiesel production from these two residue streams may be expressed as equivalent to 22% of arable land in Ireland under oilseed rape. (C) 2010 Elsevier Ltd. All rights reserved.