Aqueous amine based CO2 capture processes are the the leading technology for the CO2 emission reduction from the fossil fuel combusted power stations, but its commercial-scale application is largely limited by the intensive energy consumption associated with the capture process. While the CO2 absorption heat is identified the largest exergy destruction, the present study proposed a metal mediated electrochemical process to harvest the CO2 absorption enthalpy into electric power to compensate the capture energy consumption. Ammonia as the promising absorbent for CO2 capture was used to explore the energy conversion performance. The effect of metal types, ammonia concentrations, supporting electrolyte concentrations on the power density performance was investigated. The battery discharge performance was carried out by connecting the external load to the battery. The energy output of 4.1 kJ/mol CO2 was achieved experimentally at studied conditions, resulting in an enthalpy-to-electricity conversion efficiency of 6.4%.