Analysis of alternative non-catalytic processes for the production of biodiesel fuel

One of the most common supercritical processes for the production of biodiesel fuel involves the use of methanol as reactant. Besides obtaining biodiesel fuel, glycerol is also produced. To avoid the production of glycerol as by-product, alternative reactants for the production of the biofuel have been proposed in recent years. As expected, the use of different reactants may have an impact on the separation processes required to obtain biodiesel fuel complying with international standards. Thus, in this work flowsheets for the different supercritical processes for the production of biodiesel are proposed and analyzed in a simulation environment. The analyzed processes are then compared in terms of energy requirements, total annual costs, and environmental impact. It has been found that the two-step processes show advantages in terms of CO₂ emissions, but in terms of total annual cost the one-step processes are better, showing potential for low CO₂ emissions. Nevertheless, the processes in one-step (with methanol or methyl acetate) result in lower CO₂ emissions and TAC if they are operated at lower temperature. Acetic acid process is the more energy-intensive and expensive of the four processes.