Multi-criteria sustainability assessment of potential methanol production processes

Due to rapidly increasing world population and growing energy demands, the development of cleaner technologies to exploit renewable energy systems has become of primary importance in the collective efforts to reduce greenhouse gases emissions. The chemical conversion of renewable power into synthetic liquid fuels, such as methanol, allows an easier storage and transportation and avoids any fluctuating issues. Alternative process routes for methanol production other than from raw materials derived from fossil fuels have, during the past decade, grown in interest, where valorising the carbon capture and utilization concept and promoting synergies with the oil & gas industry are potentially achieved. The aim of this study is, in this regard, to investigate the sustainability aspects of alternative processes for synthetic methanol synthesis by applying a systematic methodology based on multi-criteria performance indicators (such as technological, economic, environmental and inherent safety). A total of eleven alternative methanol production schemes, based on synthetic methane or carbon dioxide transformation, are considered, analyzed and comparatively evaluated. The present results demonstrate that the process schemes using catalytic hydrogenation of carbon dioxide offers the best performance when considering a methanol capacity of 500 kg/h. A sensitivity analysis based on the Monte Carlo approach is also performed to verify the robustness of the results.