Current trends and prospects in microalgae-based bioenergy production

Algae are fast-growing, microscopic, and eukaryotic organisms that can perform photosynthesis, and simultaneously fix atmospheric CO2. Algal cells contain high quantity of biofuel precursors such as starch and lipid granules. In the past decades, microalgal biomass has emerged as a potential feedstock for bioenergy generation. In the current scenario, it is being extensively explored to produce liquid (bioethanol, biodiesel) and gaseous (biomethane, biohydrogen) fuels. Algal technology has four crucial aspects including strain selection and its cultivation, harvesting techniques, conversion routes, and pretreatment of biomass. The quality and quantity of biomass, available media source, cultivation system as well as environmental conditions collectively help in the selection of the specific algal strain. Despite several in-depth attempts, there are various hurdles and limitations to make algal biofuel technically and economically viable. To meet the operational and economic feasibility, a collective approach is desirable. The present state-of-the-art review deals with all four crucial aspects of algal technology. The manuscript especially covers the significant methods of harvesting, energy conversion, and pretreatment. Moreover, it also revels the advantage of biological agent mediated harvesting, energy conversion and the pretreatment of algal biomass for sustainable biofuel recovery. The prime objective of this review is to give an insight into the aspects of algal technology to promote collective research in the area of algal biofuel.