Modeling and Techno-economic Assessment of the Sustainable Methanol Synthesis

Abstract

Greenhouse gas emissions, especially the carbon dioxide out of fossil fuel combustion, has a significant annual inclination. Methanol economy, as proposed by Prof. George Olah, offers a sustainable solution for such a condition. Captured carbon dioxide and electrolytic hydrogen can react to form methanol, where methanol acts as the main hub for the carbon neutral cycle. There are two options for synthesizing methanol, the one-step direct CO2 hydrogenation process, and the two-step CAMERE process via Reverse Water-Gas Shift (RWGS) reaction. This study analyzes the two processes techno-economically, in order to find the best alternative for producing the sustainable methanol. The first step was modeling and simulation of both processes in AspenPlus® environment. Techno-economic assessment was thereafter conducted using the German Aerospace Center (DLR) in-house tool, TEPET. Net production costs of CAMERE were 2.02 €/kg or €2.84 per liter of gasoline equivalent. The one-step process resulted in less than 1 ct€ cheaper net production costs than CAMERE. Operational expenditures from electricity were the main part (around 65%) of the total production costs for both processes. Direct CO2 hydrogenation had higher Power-to-Liquid efficiency of 39.1%. However, CAMERE showed better technical performance in terms of methanol selectivity and net used CO2, where the system carbon conversion reaches 93.5% and 87.6% of total captured CO2 converted to methanol. Furthermore, CAMERE resulted in a higher Hydrogen-to-Liquid efficiency of 81.4%. In conclusion, CAMERE process is the design recommendation for the sustainable methanol synthesis plant.