Abstract
To ensure the sustainability of the biofuel chain, regulatory criteria and greenhouse gas (GHG) emissions targets have been defined by various legislative frameworks. This study used five emission allocation principles to determine the GHG emission reduction factors for rapeseed methyl ester (RME) and rapeseed oil ethyl ester (REE): total GHG emissions from the biorefinery; energy contained in the product (Eno); for each sub-process, emissions from the process inputs were allocated based on the energy from the process outputs; the avoided energy supply-related emissions were deducted using the energy allocation model described in this work; and all GHG emissions from rapeseed production were allocated to biodiesel, glycerin, and rapeseed meal. RME yields a more significant reduction in hydrocarbon emissions (by 74%) compared to REE (53%). The use of pure RME reduces CO emissions by 5.7% compared to fossil diesel fuel. The use of pure REE reduces CO emissions by 7.2%. The smoke density decreased by 68.4% (RME) and 72.6% (REE) compared to that measured for fossil diesel fuel. Hence, the amount of nitrogen and carbon oxides emitted and the smoke density of rapeseed oil ethyl ester have a lower negative impact on the environment compared to rapeseed oil methyl ester.