A Novel Multifunctional Energy System (MES) for $CO2$ Removal With Zero Energy Penalty

This paper proposes a novel, multifunctional energy system (MES), in which hydrogen and electricity are cogenerated and about 90% of $CO2$ is removed. By integrating the methane/steam reforming reaction and combustion of coal, the natural gas and coal are utilized synthetically, and coal is burned to provide high-temperature thermal energy to the methane/steam reforming reaction. Afterwards, the resulting syngas enters a pressure swing adsorption (PSA) unit to separate about 70% of hydrogen, thereby significantly increasing the concentration of carbon dioxide from nearly 20% to 43% in the PSA tail gas. As a result, the overall efficiency of the new system becomes 63.2%. Compared to a conventional natural gas-based hydrogen plant and a coal-firing steam power plant without $CO2$ removal (the overall efficiency of the two systems is 63.0%), the energy penalty for $CO2$ removal in the new system is almost totally avoided. Based on the graphical exergy analysis, we propose that the integration of synthetic utilization of fossil fuel (natural gas and coal) and the $CO2$ removal process plays a significant role in zero energy penalty for $CO2$ removal and its liquefaction in the MES. The result obtained here provides a new approach for $CO2$ removal with zero or low thermal efficiency reduction (energy penalty) within an energy system.