CO2 regenerative battery for energy harvesting from ammonia-based post-combustion CO2 capture

Abstract Amine-based CO 2 capture is considered the most mature technology for industrial application in coal-fired power stations, but its large energy requirement represents a major barrier to commercial deployment. Here, we introduce a novel approach involving a CO 2 regenerative amine-based battery (CRAB), which harvests the chemical energy from amine-based CO 2 capture through a metal-mediated electrochemical process. The CRAB process uses the dual ability of amines (i.e. ammonia) to reversibly react with CO 2 and complex with metal ions (i.e. copper) to convert the CO 2 reaction enthalpy into electrical energy. To determine how the CRAB process harvests energy from CO 2 capture, we established a validated chemical model for CRAB system which was used to predict the electrode potentials, and conceive a CRAB cycle that links CO 2 absorption/desorption with the electrochemical process. Modelling results indicate that CRAB could at best produce 8.4 kJ e /mol CO 2 from a copper/ammonia based energy harvesting system, while optimised CRAB experimentally discharged 6.5 kJ e /mol CO 2 of electrical energy with a maximum power density of 32 W/m 2 . When CRAB is coupled with an advanced ammonia process, the experimentally achieved energy output could reduce capture energy requirement to 0.177 MW h/tonne CO 2 (including CO 2 compression to 150 bar), with a high thermodynamic efficiency of CO 2 capture of 62.1% (relative to thermodynamic minimum work of 0.11 MW h/tonne CO 2 ). Our results demonstrate the technical feasibility of the CRAB system to harvest electrical energy from CO 2 capture process, providing a pathway to significantly reduce capture energy requirement.