A techno-economic analysis based upon a parametric study of alkali-catalysed biodiesel production from feedstocks with high free fatty acid and water contents

Abstract

TEAs (Techno-economic Analyses) were performed for various conditions for one-step homogeneous base catalysis of refined and low-grade vegetable oils containing moderate to high free fatty acids (FFAs) and water. The conditions modelled were based upon a “Design of experiments” study of the reaction using a meso-OBR, a continuous process screening device to rapidly screen through conditions. For refined rapeseed oil, 99% conversion to FAME was achieved at 13:1 methanol-to-oil molar ratio, 0.5 wt. % of catalyst, 50 °C and 16 min. For low-grade RSO (2.75 wt.% FFA) up to 90%, FAME was attained at 18:1 methanol-to-oil molar ratio, 2 wt% catalyst, 50 °C and 4.25 min. The TEAs were based on plant capacities of 100,000 te/y, assuming a 20 yr plant lifetime. The outputs were compared to the conventional one-step biodiesel process and a two-step process for high FFA feedstock involving a pre-treatment step to reduce FFA content, followed by alkali-catalysed transesterification. The single-step process for low quality RSO at conditions identified here, which was significantly more economically viable than the conventional process using refined oil and the two-step process using waste cooking oil.

Keywords:

• Biodiesel
• homogeneous base catalysis
• mesoscale oscillatory baffled reactors
• techno-economic analysis
• Design of Experiments

Acknowledgment

The authors would like to thank the Higher Committee for Education Development in Iraq (HCED) for their financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).