One-Pot Algal Biodiesel Production in Supercritical Carbon Dioxide

To advance the realization of algae as a feedstock for biodiesel, process technologies and closed-loop biomass use must be optimized. Life-cycle analysis (LCA) of the biodiesel production process highlights the potential significant impact of improvements in the extraction of algal lipids and conversion into biodiesel. Further, a single-step lipid extraction and transesterification process was shown to have the highest energy rewards. This work investigates the potential for using scCO2 for the extraction and conversion process. scCO2 is shown to be an effective and selective solvent for extracting triglycerides from algal biomass. This work also explores the fundamental science necessary to achieve a one-pot approach that both extracts and transesterifies lipid from algae using supercritical carbon dioxide/methanol (scCO2/MeOH) and heterogeneous catalysts. A variety of basic and acidic heterogeneous catalysts have been surveyed for their effectiveness at transesterification of triglyceride (TG) to fatty acid methyl esters (FAME). Further the enhanced solubility of FAME over reaction intermediates, TG, and glycerol, is likely to provide a driving force for reaction. This research offers the foundations for a simple one-pot system wherein biodiesel can be directly, selectively, and sustainably produced from algae for further application in an algae