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To address issues related to climate crises, microalgae-based biofuels are considered a promising option for reducing carbon dioxide emissions in the transportation sector. However, despite extensive research conducted over the past 20 years, there are major limitations in the application of conventional algal biodiesel, such as the instability of oxygen-containing fuel, blending wall limitations (less than 20%), and poor cost competitiveness. Recently, biomass-based renewable hydrocarbon fuels (drop-in biofuels) have been considered technologically competitive alternatives to petrofuels owing to the advantages of carbon dioxide reduction, high energy density, and compatibility with existing infrastructure. This review discusses the integrative utilization of whole algal biomass for the development of an advanced algal biorefinery process that could strategically help produce drop-in biofuels and multiple by-products to meet the growing fuel demand and secure economic feasibility. This review provides an updated overview of recent technical advancements in the (1) mass cultivation of oleaginous algal biomass obtained from industrial wastes, (2) production of renewable biodiesel and bio-jet fuel using algal lipids via catalytic upgrading, and (3) diversification of bio-products generated from residual lipid-extracted biomass, such as hydrogen, methane, alcohols, bio-oils, organic acids, biosorbents, biomaterials, and nutrients. The challenges and prospects for practical application are discussed along with the major constraints on the commercialization of integrative algal biorefining. [Display omitted] • Integrative utilization of whole biomass is required for economic algal biorefining. • Mass cultivation of lipid-rich algal biomass using CO 2 -rich flue gas and wastewater. • Catalytic upgrading of renewable diesel and bio-jet fuel from algal neutral lipids. • Diversification of products from lipid-extracted biomass via subsequent conversions. [ABSTRACT FROM AUTHOR]

Abstract: High-cost downstream process is a major bottleneck for producing microalgal biodiesel at reasonable price. Conventional lipid extraction process necessitates biomass drying process, which requires substantial amount of energy. In this regard, lipid extraction from wet biomass must be an attractive solution. However, it is almost impossible to recover lipid directly from wet microalgae with current technology. In this study, we conceived osmotic shock treatment as a novel method to extract lipid efficiently. Osmotic shock treatment was applied directly to wet Chlamydomonas reinhardtii biomass with water content >99%, along with both polar and non-polar organic solvents. Our results demonstrated that osmotic shock could increase lipid recovery approximately 2 times. We also investigated whether the presence of cell wall or different cell stages could have any impact on lipid recovery. Cell wall-less mutant stains and senescent cell phase could display significantly increased lipid recovery. Taken together, our results suggested that osmotic shock is a promising technique for wet lipid extraction from microalgal biomass and successfully determined that specific manipulation of biomass in certain cell phase could enhance lipid recovery further. [Copyright &y& Elsevier]