Biofuel production from microalgae: a review

The shortage of fossil fuels is actually a major economic issue in the context of increasing energy demand. Renewableenergies are thus gaining in importance. For instance, microalgae-based fuels are viewed as an alternative. Microalgae aremicroscopic unicellular plants, which typically grow in marine and freshwater environments. They are fast growing, havehigh photosynthetic efciency, and have relatively small land requirement and water consumption in comparison with con-ventional land crops biofuels. Nonetheless, selling biofuels is still limited by high cost. Here, we review biofuel productionfrom microalgae, including cultivation, harvesting, drying, extraction and conversion of microalgal lipids. Cost issues maybe solved by upstream and downstream measures: (1) upstream measures, in which highly productive strains are obtainedby strain selection, genetic engineering and metabolic engineering, and (2) downstream measures, in which high biofuelsyields are obtained by enhancing the cellular lipid content and by advanced conversion of microalgal biomass to biofuels.Maximum biomass and high biofuels production can be achieved by two-stage culture strategies, which is a win–win approachbecause it solves the conficts between cell growth and biomass accumulation.