Multi-objective design of a new sustainable scenario for bio-methanol production in Brazil

Abstract

The objective of this work is to investigate the technoeconomic feasibility of a new sustainable bio-methanol production scenario from renewable sources using carbon dioxide captured from the fermentation process in ethanol production distilleries, carrying out an integrated analysis of the overall system. The hydrogen required is provided electrolyzing treated water of the distilleries and producing oxygen as a valuable byproduct. Aiming to promote carbon capture processes, an industrial methanol plant was modelled with Aspen Plus® and optimized using Matlab®. Design parameters were handled taking into account the associated capital costs and applying sensitivity analysis. The response surfaces were obtained according to the amount of bagasse used to cogenerate energy, attempting to maximize the Net Present Value while minimize the CO2 emissions of each scenario. The results show that the problem of high-energy consumption for electrolysis might be bypassed using co-generated energy, being feasible to implement this process in distilleries able to emit more than 120,000 tonne/harvest of CO2. Depending on the distillery size, a range of 1136–1988 tonnes of methanol can be produced per year at production costs in the range of 0.51–0.62 $/kg with a negative CO2 balance varying from −2198 to - 1814 tonne/yr. The purposed scenario indicates that integrating a methanol plant with an ethanol distillery is an innovative option for carbon mitigation in Brazil compared to other studies, contributing to the sustainable production of methanol.