A review on prospective production of biofuel from microalgae

• Challenges faced in I generation biofuels and transition to II generation biofuels. • Microalgae as a feedstock for biofuel production has been discussed in this review. • Two stage cultivation strategies and extraction techniques were discussed. • HTL, fermentation, transesterification and pyrolysis of III generation biomass in briefly analyzed. This critical review summarizes the utilization of algae as the resilient source for biofuel. The paper validates the different stages in generation of biofuels and provides a clarity on III generation biofuels. The microalgae is focused as an incredible source and a detailed discussion has been carried out from the cultivation, extraction and conversion to the final product. An elaborate view on conversion methodologies and troubles involved in the respective techniques are presented. The efficiency of the algal fuel performing in I/C engines derived from major techniques is considered. There exist new challenging barriers in the implementation of microalgae as prospective source in the energy market. In addition, types of pyrolysis for the production of main product from microalgae had been discussed in detail. Besides, some microalgae grow easily from fresh to waste water, make it more feasible source. Although the microalgae are a best alternative, cost of production and the yield of biofuel are still challenging. Further, cultivation of microalgae is very effective by applying two stage cultivation strategies. This comprehensive review provides the useful tool to identify, innovate and operate microalgae as the potential based biofuel.