Selection of oil extraction process from Chlorella species of microalgae by using multi-criteria decision analysis technique for biodiesel production

In the last few decades, the energy crisis has been one of the main concerns related to the lack of long-term petroleum-based reserves as primary energy resources. Biodiesel emerged as a promising alternative. Nowadays, it is produced from edible vegetable oil, thereby causing commodity prices and food security disruption. In this case, microalgae serve as a sustainable and renewable feedstock for their fast growth, high lipid content, and CO2 absorbing agent. Five processes are applied on the production of microalgae-based biodiesel, namely cultivation, harvesting, extraction, conversion, and refinement. There is currently limited study on technology selection on industrial-scale technology for oil extraction from Chlorella spp. of microalgae. Therefore, this study aims to review and select the most suitable technology using simple multi-attribute rating technique extended to ranking - multi-criteria decision analysis (SMARTER-MCDA). Preliminary studies showed that conventional organic solvent extraction (COE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), electric pulse extraction (EPE), supercritical fluid extraction (SFE), and hydrothermal liquefaction (HTL) were the most promising technologies. These technologies required a series of evaluations using SMARTER-MCDA with several criteria, including easy scalability, extraction productivity, energy input, additional compound, and environmental impact. The result ranking showed that MAE technology was selected as the most suitable technology for oil extraction from Chlorella spp.