Innovative alternatives to methanol manufacture: Carbon footprint assessment

Finding and implementing more sustainable alternatives to the fossil-dependence routes for methanol (MeOH) manufacturing is undoubtedly one of the challenges of our model of society. Some approaches can be used to convert CO2 into MeOH as direct hydrogenation or electrochemical reduction (ER). These alternatives lead to lower natural resources consumption respect the conventional routes, but they are still found at different technological readiness levels (TRLs). Therefore some remaining challenges need to be overtaken to achieve a carbon neutral cycle respect the conventional route, especially in the case of ER, which is currently found at its infancy. This would indicate their final industrial competitiveness in a sustainable mode. This study uses Life Cycle Assessment as the main tool in order to compare these two CO2-based manufacture alternatives (found at different TRLs) with the fossil-route. The results allow for evaluating the potential challenges inherited to the alternative based on ER. Utilization of renewable energy is one of the most important key issues to achieve a carbon neutral product using these options. However, its benefit could be neglected due to the high requirement of steam in the purification step, particularly in ER. It was demonstrated that a future scenario using ER leads to a lower natural resources consumption (mainly natural gas) compared to the conventional fabrication, which represents an important step towards more green and efficient MeOH synthesis. (C) 2019 Elsevier Ltd. All rights reserved.