Techno-economic evaluation of palm stearin biodiesel production using a continuous deglycerolization reactor

Abstract

The growing reliance on edible oils for biodiesel production raises concerns regarding feedstock availability and cost volatility. Palm stearin (PS), a by-product of palm oil fractionation with reduced demand in food applications, offers an attractive alternative feedstock for biodiesel production. In this study, biodiesel was produced from PS using a continuous deglycerolization reactor (CDR), which removes glycerol during transesterification. The optimal process condition was a methanol–oil molar ratio of 5:1, a potassium methoxide (KOCH₃) catalyst loading of 1.2 wt%, a mixing speed of 250 rpm and a glycerol removal rate of 0.25 L h⁻¹. Under these conditions, the CDR produced high-quality biodiesel with an ester content of 97.23 wt% and a yield of 98 wt%. An economic assessment indicated a positive net present value, an internal rate of return above 8% per year, and a payback period of 1.12 years. Sensitivity analysis showed that economic performance is influenced by production cost and biodiesel selling price, with a break-even selling price of US$0.99 L⁻¹. The combination of reduced methanol consumption and the use of lower-cost PS support the economic viability of the proposed process.