Sustainability of sunflower cultivation for biodiesel production in Tuscany within the EU Renewable Energy Directive

The European Union Renewable Energy Directive 2009/28/EC (RED) has adopted climate change assessment as one of the environmental criteria used to evaluate the level of sustainability by indicating the impact values for every phase of the biofuel chain. This paper shows the results of a Life Cycle Assessment (LCA) of greenhouse gas (GHG) emissions from cultivation of sunflower for biodiesel production in Tuscany, Italy. In the five case studies, the GHG emissions of sunflower cultivation exceed the default value (18 g [CO2eq] MJ−1) indicated by the RED. This is mainly due to diesel consumption and emissions from nitrogen fertilisers that are on average 180% and 255% higher than the reference values, respectively. GHG emissions allocation among sunflower biodiesel and co-products was made according to energy content principle. Only the biodiesel from sunflower cultivated in the two most efficient farms achieved a GHG saving with respect to conventional diesel (36%) that made it possible to fulfil the RED's requirements. From these results, it seems that the observance of such requirements on GHG emissions for sunflower biodiesel cultivation phase in Tuscany will not be easy to satisfy without a significant revision of local farm practices, aimed primarily at reducing the use of nitrogen fertilisers and diesel consumption. In fact, the GHG emissions reported in the RED for sunflower cultivation were calculated using excessively low farm inputs compared with the typical amounts for sunflower cultivation practices in Tuscany.

► GHG emissions from cultivation of sunflower for biodiesel are investigated.
► Two farms out of five achieve a GHG saving in line with Renewable Energy Directive.
► Emissions due to diesel and nitrogen fertiliser are much higher than reference values.
► Default cultivation performances appear to be hardly achievable.
► Assumption of default emission values may result misleading in many study cases.