Evaluation and optimization of feedstock quality for direct conversion of microalga Chlorella sp. FC2 IITG into biodiesel via supercritical methanol transesterification

The study reports evaluation of feedstock quality for direct conversion of microalga Chlorella sp. FC2 IITG into biodiesel via supercritical methanol transesterification (SCMT). Characterization of biomass feedstock quality on fatty acid methyl esters (FAME) yield was performed based on two key parameters: intracellular lipid content and water content of the biomass. Statistical optimization of transesterification parameters, e.g., lipid content, water content of biomass, and methanol loading, predicted the optimum values of 52% (w/w), 5.75 mL g−1, and 115 mL g−1, respectively, with maximum FAME yield of 96.9%. This improved FAME yield was achieved with much lower methanol loading and higher water content per gram of biomass and hence offers elevated economic feasibility via minimizing the utilization of alcohol and enabling direct conversion of wet algal biomass into biodiesel. FAME produced via SCMT satisfied most of the biodiesel properties as per ASTM and European standards thereby referring to good quality biodiesel.