Approaches for Optimising the Greenhouse Gas Balance of Biodiesel Produced from Rapeseed
(IEA Bioenergy Task 39) On the request of the UFOP, the DBFZ examined several approaches to improving the Green-House-Gas (GHG) saving balance of biodiesel produced from rape seed. The work was based on the so called default values for biodiesel from rape seed in Annex V of the EU Directive on the Promotion of the Use of Energy from Renewable Sources (2009/28/EC). According to this default value, the GHG emission saving of biodiesel amounts to approx. 38 % in comparison with fossil fuels.
The target of the study was, at first, to develop an understanding for the data base and the method of calculation adopted in the EU Directive 2009/28/EC for arriving at the default value for biodiesel from rape seed and then identify possible approaches to optimisation of the balance calculation. As expected, the main factors impacting the overall result on the level of rape seed production was the production and use of industrial fertilizer and, on the level of rape seed oil extraction and transesterification, the input of heat, electricity and methanol.
The theoretical optimisation potential of the GHG balance was calculated for all stages of the process chain by sensitivity analysis. For example, in the calculation of a typical case, emissions from the process of cultivation were reduced theoretically from approximately 29 g CO2 equ./MJ biodiesel (which corresponds to the default value in the Directive) to approx. 21 g CO2 equ./MJ biodiesel by varying the fertiliser and the diesel fuel used in the agricultural machines. The theoretical „total optimisation potential“ calculated by the study yields a GHG emission value of approx. 28 g CO2 Equ./MJ biodiesel, which is about 46 % below the default value for rape seed biodiesel in Annex V of the Directive – a substantial reduction. This result corresponds to a GHG emission saving of the order of 67 % in relation the reference value for fossil diesel (83.8 g CO2 equ./MJ). READ MORE and MORE