The biomethane, silage and biomass yield obtainable from three accessions of Cynara cardunculus

In the light of the possible contribution of bioenergy to reducing the dependence on fossil fuel imports and to controlling greenhouse gas emission, a present priority is to develop crops which can be raised using minimal production inputs. The potential of the cardoon (Cynara cardunculus) has been investigated here by assessing the outcome of anaerobically digesting two cultivated forms and one wild one. Fermentation lab tests were performed on ensiled biomass, as in the real scale conditions, and they were aimed at measuring the biomethane production per unit of feedstock. The cultivated forms (‘Altilis 41’ and ‘Bianco avorio’) produced, respectively, 19.1 and 16.8 t dry matter (DM) per hectare per year, from which, respectively 4074 and 4162 Nm3 of biomethane was generated; the wild cardoon accession was less productive both in terms of biomass accumulation (11.8 t DM per hectare per year) and estimated biomethane yield (2867 Nm3). The yield of biomethane ranged from ∼200 (‘Altilis 41’) to 245 (‘Bianco avorio’ and wild cardoon) Nm3 per t DM, a level sufficiently high to justify considering C. cardunculus as a promising candidate bioenergy crop in the Mediterranean environment.