A Comparison of Costs of Biodiesel Production from Transesterication

Abstract

Nowadays, biodiesel is well accepted as a renewable energy. However, the high production cost of biodiesel is a remaining problem. The preliminary economic design in this work aimed to determine the optimal operating condition by using HYSYS 3.2 software. The transesterification of triglyceride (oil) and methanol to produce methyl ester (biodiesel) was the reaction used in the simulation. The study includes the recovery of the excessive methanol from all units in the process. The studied parameters affecting the purity of the production and the operating cost in this work were reaction times (2-60 minutes), reaction temperatures (55 ^oC-75 ^oC) and molars ratios of alcohol to oil (6:1-10:1). Moreover the work considered the size and number of the reactors that can improve the purity of the product. The study found that the optimal condition that minimizes the operating cost is the ratio of methanol to oil at 6:1 (or 0.238:1 by wt.), the reaction temperature at 70 ^oC, and the reaction time of 20 minutes. In addition, for the same production rate, the process with double size of the reactor improves the product purity (from 96.62 % to 98.21 %). For the number of reactors, it is found that two half-size reactors give better product purity and operating cost than the single reactor with the equivalent size.