Techno-economic assessment of a cost and quality-based algal biodiesel production process

The biggest obstacles to replacing petroleum-based diesel with less-polluting biodiesel are its cost and use of arable land for feedstock production, namely food crops. Microalgae are more suitable since they don’t require arable land; however, currently it is not cost-effective, and few previous studies have analyzed its quality. To overcome these two crucial challenges, we developed a novel Cost and Quality-based Algal Biodiesel Production Process (abbreviated as CQ-Biodiesel), which produces cost-effective biodiesel while exceeding the minimum quality defined by American Standards for Testing and Materials. CQ-Biodiesel is modeled in SuperPro Designer, implementing an innovative approach where we shift focus from product retention (as in previous research) to overall cost-effectiveness. This enables minor sacrifices in productivity for maximal overall energy efficiency, attaining 98.49%. A hybrid cultivation stage is introduced in this study to maximize lipid productivity at 0.13 g/L/day, a 10% increase compared to previous studies. A closed-loop hexane extraction method is developed to decrease solvent pollu- tion by 99.4% compared to previous studies. In the US, the computed selling price is $4.71/gallon, 15% less than diesel. The present study reveals that the CQ-Biodiesel model significantly improves upon existing algal biodiesel production processes in three key aspects—cost, quality, and reduced envi- ronmental impact.