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 <i>Nannochloropsis salina</i> 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