A comprehensive review on microalgal biomass production and processing for biodiesel production

Biodiesel is considered a promising alternative to conventional fuels in response to increasing global energy demands, and it also contributes to reduced environmental emissions. Microalgae is a potential resource for qualitative biodiesel production due to its high specific growth rate, ability to accumulate significant quantities of intracellular lipids, potential to utilize wastewater as a cultivation medium and less cropland requirement compared to conventional oil crops. However, the commercialization of microalgae biodiesel largely depends on the energy and cost-efficiency of the microalgae cultivation system. Moreover, optimization of cultivation systems and strain improvement in microalgae are promising strategies to enhance the growth rate and lipid productivities. This review provides a comprehensive overview of the various microalgae cultivation systems, focusing on the recent developments, including the genetic engineering perspectives in improving microalgae growth and lipid productivity, techno-economic analysis, and real case studies for microalgal biodiesel production. The review paper also summarizes the microalgae harvesting and lipid extraction processes, transesterification methodologies, quality of microalgae biodiesel, and environmental concerns associated with the large-scale production of microalgae biodiesel.