Techno-economic and exergy analysis of polygeneration plant for power and DME production with the integration of chemical looping CO2/H2O splitting

In this paper, we present a novel polygeneration plant with carbon capture for the combined power and dimethyl ether (DME) production. The plant layout integrates a chemical looping CO2/H2O splitting (CL) unit producing syngas (CO and H2) for the DME synthesis using the exhaust gases of an oxyfuel power cycle. The primary power is generated by oxy-combustion of syngas generated by the reduction of the metal oxide in the reduction unit of the CL redox cycle with incoming natural gas. The oxyfuel power plant also generates steam for combined power production with two streams Rankine cycles. The aim of the present work is to assess the process on the basis of energy and exergetic efficiency and economic performance of the integrated CL unit for combined power and DME production. The integration proposed resulted in a production of 103 MWe and 185.6 ton/day (2.15 kg/s) of DME. The corresponding energy and exergetic efficiency was 50.2% and 45%, respectively. A discounted cash flow analysis was performed to evaluate the profitability of the process. With a carbon credit of $80/tonne, the plant would be able to meet the current electricity with carbon capture and DME prices of $50/MWh and $18/GJ respectively. The economic analysis provided information on the main economic drivers associated with the high capital investment in the process plant with individual sub-systems. The analysis highlighted the strong potential of integrating chemical looping CO2/H2O splitting for syngas production into polygeneration systems to increase the overall efficiency while reducing the cost of carbon capture.