Production of methanol and organic carbonates for chemical sequestration of CO2 from an NGCC power plant

Abstract

Global economic development anticipates a growth in demand of the energy sector whose supply in the coming decades will remain achieved by burning fossil fuels. The need to stabilize the CO2 atmospheric concentration requires technologies for capturing and reutilization of this greenhouse gas. Such scenario motivates feasibility analysis of power generation with post-combustion capture of CO2 from the flue gas associated with its transformation into chemical commodities. Specifically, the economic performance of an integrated NGCC with post-combustion capture and utilization is evaluated to balance aggregated revenues with energy penalty. The proposed CO2 reutilization is the production of methanol (MeOH), organic carbonates—dimethyl carbonate (DMC) and ethylene carbonate (EC), and ethylene glycol (EG). The study uses CO2 capture with MEA (monoethanolamine), including compression of the captured gas followed by its conversion to methanol and organic carbonates, and separation of products with recycle of reactants. Three scenarios were evaluated corresponding to the capture of 30, 50, and 80 % of the CO2 present in the flue gas. The comparative analysis includes definition of design premises followed by synthesis of process flowsheet, process simulation in the three scenarios, with sizing of the main pieces of process equipments for economic analysis—capital and operational expenditures (CAPEX and OPEX). Results indicated economic feasibility for the three scenarios. Furthermore, energy and mass balances showed that the emissions from energy demand to drive reactions and separations surpasses the proposed sequestration of CO2 by chemical utilization in the scenarios of 30 and 50 % of CO2 capture from NGCC emissions. In reality, CO2 accounting for cases 1 and 2 reveals a “carbon debt” while for case 3 a net positive abatement of CO2 occurs which increases process revenue by 1.7 % and reduces ROI in 1 year.