Quality of residues of the biodiesel chain in the energy field

• The quality of residues deriving from biodiesel chains has been evaluated.
• The high number of samples guarantee for representative results.
• Crop residues have the most energy potential in quantitative terms.
• Crop residues should be employed in medium-large sized plants to limit problems.

The first generation biofuels still have the role of leader in global production of biofuels. In Europe biodiesel is produced mostly from rapeseed (Brassica napus L. oleifera Metzg) and sunflower (Helianthus annuus L.). The EU policy is giving attention to the valorization of residues deriving also from those chains. The present work had the objective of evaluating the quality of residues deriving from biodiesel chains based on rapeseed and sunflower crops as well as on other interesting crops in the Mediterranean area, such as Ethiopian mustard (Brassica carinata A. Braun) and cardoon (Cynara cardunculus L.). For this purpose an energetic characterization of straws, hulls and press cakes were performed following the official technical normative, as well as the evaluation of their energetic potential. The energy content of residues resulted to be interesting and their quality compatible in general with an energetic use. Crop residues seem to have the most energy potential in quantitative terms, and their exploitation can improve the energy balance of first generation biodiesel production chain improving their sustainability. Concerning quality, crop residues should be employed in medium-large sized plants to limit problems related to plant management and emissions.