Simplifying biodiesel production from microalgae via wet in situ transesterification: A review in current research and future prospects

Abstract

This work aims to thoroughly review current research in in situ transesterification (ISTE) targeting biodiesel (fatty acid alkyl ester) using wet microalgae. In ISTE, the variable conditions are highly dependent on the water contained in raw microalgae. Nevertheless, the water content in most ISTE review article was overlooked only as one of process variables. Hence, this review focused on research regarding wet ISTE technologies using microalgae. Here, the developed technologies are classified on the reaction temperature applied; the increment in the temperature of wet ISTE compensates for the hindrance of water, therefore wet ISTE tends to have distinct features depending on the reaction temperature. The detailed variables or reaction conditions are characterized by the three different reaction temperature zones of low (under 100 °C), middle (101–200 °C), and high (above 200 °C). The future prospects of wet ISTE are suggested based on the techno-economic analysis (TEA) of existing works that used wet Nannochloropsis gaditana. This work can assist in understanding the current technologies of wet ISTE and how to make wet ISTE forwarded for the sustainable production of algal biodiesel.