Methanol synthesis using captured CO2 as raw material: Techno-economic and environmental assessment

Abstract

The purpose of this paper is to assess via techno-economic and environmental metrics the production of methanol (MeOH) using H2 and captured CO2 as raw materials. It evaluates the potential of this type of carbon capture and utilisation (CCU) plant on (i) the net reduction of CO2 emissions and (ii) the cost of production, in comparison with the conventional synthesis process of MeOH Europe. Process flow modelling is used to estimate the operational performance and the total purchased equipment cost; the flowsheet is implemented in CHEMCAD, and the obtained mass and energy flows are utilised as input to calculate the selected key performance indicators (KPIs). CO2-based metrics are used to assess the environmental impact. The evaluated MeOH plant produces 440ktMeOH/yr, and its configuration is the result of a heat integration process. Its specific capital cost is lower than for conventional plants. However, raw materials prices, i.e. H2 and captured CO2, do not allow such a project to be financially viable. In order to make the CCU plant financially attractive, the price of MeOH should increase in a factor of almost 2, or H2 costs should decrease almost 2.5 times, or CO2 should have a value of around 222€/t, under the assumptions of this work. The MeOH CCU-plant studied can utilise about 21.5% of the CO2 emissions of a pulverised coal (PC) power plant that produces 550MWnet of electricity. The net CO2 emissions savings represent 8% of the emissions of the PC plant (mainly due to the avoidance of consuming fossil fuels as in the conventional MeOH synthesis process). The results demonstrate that there is a net but small potential for CO2 emissions reduction; assuming that such CCU plants are constructed in Europe to meet the MeOH demand growth and the quantities that are currently imported, the net CO2 emissions reduction could be of 2.71MtCO2/yr.