Sustainability assessment of microalgal biodiesel production processes: an exergetic analysis approach with Aspen Plus

Biodiesel production growth rate keeps increasing every year with the hope of replacing fossil based liquid fuel which is near exhaustion. Energy efficiency methods coupled with environmental and economic sustainabilities would render biodiesel production attractive. Algal cultivation and oil extraction processes are found to be energy intensive hence exergy destructive. This study presents the thermodynamic feasibility of microalgal biodiesel production plant via exergy analysis. Mathematical modelling withAspen Plus shows that the centrifuge for algae-medium separation recorded the highest exergy loss of 925 MJ representing 15% of the total exergy loss. 64% of the total exergy input into the whole plant is destroyed to attain the products (biodiesel and glycerin).