Process design, techno-economic, and life cycle assessment of methanol production routes

Abstract

Methanol plays a crucial role as a versatile chemical feedstock and energy carrier. Urgent and increasing environmental impacts require exploring renewable pathways for methanol production to achieve a sustainable transition. This article evaluates five scenarios for methanol production: the conventional method (baseline – natural gas), biomass gasification-based configurations, and CO${}_2$ hydrogenation with hydrogen produced through water electrolysis. Thermodynamic analysis conducted to assess energy efficiency, with pinch analysis employed for heat integration in all pathways, effectively utilizing waste heat to enhance system efficiency and reduce environmental impacts. Life cycle assessment is conducted to evaluate the environmental impacts of each scenario, with a focus on identifying the most significant parameters influencing these impacts. Additionally, a techno-economic analysis is performed to assess the profitability of each scenario. Results indicate that the scenario of biomass-based methanol production producing biochar (BPBCB) achieves the highest energy efficiency at approximately 69%. In terms of environmental performance, the scenario of biomass-based methanol production without producing biochar (BWOBB) has the lowest impact on total human health, while CO₂ hydrogenation (DCM) demonstrates the lowest impact on total ecosystem quality. Both BWOBB and DCM scenarios exhibit the lowest climate change impacts, with 0.15 and 0.19 _CO2,eq/kg_methanol, respectively, highlighting the role of biomass and renewable hydroelectricity in mitigating climate change. Economically, the natural gas scenario is the most favorable, but among renewable methods, BPBCB achieves the best net present value of 2.043 B$ and a payback period of 6.2 years, making it the most viable alternative to fossil-based methanol production under current conditions.