Techno-economic and Sensitivity Analyses of Different Biodiesel Production Pathways by Adding Tetrahydrofuran as a Cosolvent

The main objective of this study is to design and simulate three different continuous processes, namely, homogeneous and heterogeneous alkali-catalyzed and supercritical methanolysis processes to produce biodiesel at a production rate of 100,000 t/year from virgin vegetable oil. Tetrahydrofuran (THF) was used as a cosolvent at different concentrations of 25 wt.%, 30 wt.%, and 1.63 wt. % for the homogeneous and heterogeneous alkali-catalyzed and supercritical processes, respectively. An economic assessment and a sensitivity analysis were performed based on the results of the process design and simulation. Technical assessment of the proposed processes indicated that the homogeneous and heterogeneous alkali-catalyzed processes were the simplest, where the least amount of process equipment were used. whereas the supercritical methanolysis process was more complex, which used a large number of transesterification and separation units. The homogeneous alkali-catalyzed process that used THF demonstrated the lowest total capital investment, after-tax net profit, and payback period of M$2.32, M$10.54, and 0.19 years, respectively, and the highest after-tax rate of return of 513%. However, the heterogeneous alkali-catalyzed process that used THF demonstrated the lowest manufacturing cost of M$82.20 and the highest after-tax net profit of M$18.20. The supercritical methanolysis process that used THF demonstrated the highest manufacturing cost of M$90.07 and the after-tax net profit of M$12.40. The results from the sensitivity analyses indicated that the methanol recovery percentage, biodiesel purification tower vacuum pressure, and costs of feedstock oil, methanol, biodiesel, and glycerin by-products are the factors that most significantly affect the economic feasibility of biodiesel production.

Automated summary

The main objective of this study was to design and simulate three different continuous processes for biodiesel production. An economic assessment and sensitivity analysis were performed, and the results showed that the homogeneous alkali-catalyzed process using THF had the lowest total capital investment and the highest after-tax rate of return. The heterogeneous alkali-catalyzed process using THF had the lowest manufacturing cost and the highest after-tax net profit. The supercritical methanolysis process using THF had the highest manufacturing cost and after-tax net profit.