Whole conversion of microalgal biomass into biofuels through successive high-throughput fermentation

Abstract

Microalgae represent a promising feedstock for biofuel production. However, the energy efficiency of microalgal pretreatment and conversion technologies needs to be improved to meet the economic viability. Herein, we introduce a novel integrated approach to achieve unprecedented energy conversion efficiency (46%) of microalgal biomass (Chlamydomonas mexicana). A successive high-throughput fermentation followed by transesterification were employed. This process provided a platform for maximum recovery of energy carriers from biomass utilization (89%). Serial fermentations were implemented for thorough utilization of the biomass constituents, starting with carbohydrate, followed by protein to derive ethanol (C2) and higher alcohols (C3–C5), respectively. Lipid was the dominant component after the previous fermentation, which was converted to biodiesel via transesterification process. Successive fermentations served as a bio-pretreatment to enhance the bioavailability of the leftover protein and lipid, which minimized the use of expensive and laborious methods for their extraction from the microalgal biomass. The proposed serial fermentation process would maximize the utilization of biomasses for biofuel production, with minimum leftover (11%).