Life cycle assessment of methanol production and conversion into various chemical intermediates and products

Transportation sector, particularly road transport, together with the industrial expansion stand out as key factors behind the unprecedented CO2 levels, hence the need for green fuel alternatives and sustainable technologies. The present investigation evaluates methanol (MeOH) production via direct CO2 hydrogenation, and conversion into valuable derivatives: i) formalin, ii) dimethyl ether (DME), iii) methyl tert-butyl ether (MTBE), and iv) biodiesel through modelling and simulation, as well as environmental assessment. Hydrogen is produced by water electrolysis considering three different energy scenarios: i) EU grid mix; ii) wind power; iii) hydro power. The amount of CO2 needed is obtained from cement manufacturing through a chemical scrubbing process using Methyl-Di-Ethanol-Amine (MDEA). The environmental analysis is carried out following the Life Cycle Assessment (LCA) methodology using GaBi software, and ReCiPe as impact assessment method. The key performance indexes, main product purity (>99%) and energy requirements (i.e., 1.72 MWe/t, and 5.89 MWe/t respectively) point towards alkali biodiesel, and MTBE production as the most promising MeOH conversion routes. The environmental analysis highlights that MeOH production and conversion towards alkali biodiesel process displays the lowest impact score for each energy scenario. The second-best conversion route is MTBE when using the grid mix energy scenario, and formalin when wind or hydro power is considered.