Commercial-Scale Biodiesel Production from Algae

This article evaluates pathways to cost-effective production of biofuels at a commercial scale. A thermodynamic cultivation model was simulated using Aspen Plus V7.3.1 and used to predict the area required for algae growth. This model was combined with the most promising commercial-scale methods to harvest algae and extract the oil. Conversion experiments were conducted using oil extracted from Nannochloropsis sauna algae, which was grown in salt water by Solix Biofuels. Glycerolysis was performed to reduce the free fatty-acid content of the oils. Transesterification was then carried out using a solid catalyst. Rate constants were regressed to adapt kinetic models to the rate data, which allowed the glycerolysis/transesterification process to be simulated using Aspen Plus V7.3.1. Cost estimates from the Aspen Process Economic Analyzer (APEA) were combined with industrial quotes and literature data. A cash flow analysis was performed for the entire carbon sequestration-to-biodiesel production train, yielding a biodiesel selling price of $4.34/gal. Finally, a sensitivity analysis was performed to examine the impact of various costing parameters on the viability of the process. These analyses show that the current bottlenecks for the large-scale production of biodiesel are cultivation techniques and extraction operations.