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
salina 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.