Chlorella vulgaris as a green biofuel factory : comparison between biodiesel, biogas and combustible biomass production

Biofuels are viewed as the answer to safeguard the currently challenged energy security. To this end, the present study provides a comparison between approaches regarding microalgal biomass conversion to bioenergy, with a view on sustainable implementation. The energetic valorization of Chlorella vulgaris biomass cultivated under heterotrophic, sulfur-limited conditions was investigated through the biofuels biodiesel, biogas (biomethane) and combustible dry biomass. The lipid productivity can reach the value of 442.9 6.5 mg L-1 d(-1) containing suitable fatty acids for biodiesel production. Next, biochemical methane potential (BMP) assays yielded 360.9 20.2 mL CH4 g VSadlded under mesophilic conditions, while the calorific value of dry C. vulgaris biomass was measured as 24,538 182 kJ kgpw(-1) (5,865 43 kcal kgpw(-1)). Considering the downstream processing required in each approach, the most promising energy valorization method is anaerobic digestion able to reach values up to 20,862 kJ Lreactor 1 day(-1) in continuous systems.Biofuels are viewed as the answer to safeguard the currently challenged energy security. To this end, the present study provides a comparison between approaches regarding microalgal biomass conversion to bioenergy, with a view on sustainable implementation. The energetic valorization of Chlorella vulgaris biomass cultivated under heterotrophic, sulfur-limited conditions was investigated through the biofuels biodiesel, biogas (biomethane) and combustible dry biomass. The lipid productivity can reach the value of 442.9 6.5 mg L-1 d(-1) containing suitable fatty acids for biodiesel production. Next, biochemical methane potential (BMP) assays yielded 360.9 20.2 mL CH4 g VSadlded under mesophilic conditions, while the calorific value of dry C. vulgaris biomass was measured as 24,538 182 kJ kgpw(-1) (5,865 43 kcal kgpw(-1)). Considering the downstream processing required in each approach, the most promising energy valorization method is anaerobic digestion able to reach values up to 20,862 kJ Lreactor 1 day(-1) in continuous systems.A