Ammonia-enhanced calcium looping for carbon reduction in natural gas combined cycle plants

Abstract

Ammonia co-firing and carbon capture, and storage technologies are promising alternatives for decarbonizing fossil-fueled power plants. However, ammonia co-firing is constrained by the co-firing ratio, while carbon capture technology faces challenges from high energy penalties. Thus, this study proposes a novel ammonia-driven calcium looping post-combustion capture technology for decarbonizing existing fossil fuel power plants. By utilizing the heat from the carbonation reaction of calcium looping technology to drive ammonia cracking, the system avoids inefficiencies from large temperature heat exchange during steam generation. Results show the new system achieves an efficiency penalty of 0.6 percentage points, carbon emission intensity of 18.6 kg CO₂/MWh_e, and CO₂ avoidance energy consumption of −8.1 MJ_LHV/kg CO₂, outperforming conventional systems. The system also demonstrates higher exergy efficiency (47.9 %) and lower cost of CO₂ avoided (191.1 $/t CO₂). And when the price of green ammonia decreases to 240 $/t in the future, the cost of CO₂ avoided for the new system could further drop to −28.4 $/t CO₂, presenting a substantial economic advantage over the other systems. This study provides an innovative approach for power plant decarbonization with improved efficiency and economic feasibility.