Enhancing energy security through dual CO2 capture via liquefaction and calcium looping for methane, ammonia, and carbon storage

An integrated system utilizing potential from wind energy and anaerobic digestion is developed for the simultaneous production of electricity, methane, ammonia, and carbon dioxide. A dual CO 2 capture strategy based on liquefaction and calcium looping enables efficient carbon recovery in both storable and utilizable forms. The main novelty is the synergistic integration of these complementary capture pathways within one wind–biomass framework, enabling carbon recovery, utilization, and storage. The system is further assessed using 8784 h of NASA MERRA-2 hourly wind data to evaluate wind-intermittency effects beyond a steady-state assumption. A comprehensive 4E analysis (energy, exergy, economic, and environmental) is conducted. Under baseline conditions, the system achieves an exergy efficiency of 37.47%, net power output of 4358 kW, and a specific product cost of 38.37 $/GJ, with an avoided CO 2 -based environmental index of 0.5654 kg CO 2 /kWh. Production rates include 0.09296 kg/s liquid CO 2 , 0.7223 kg/s gaseous CO 2 , 0.01323 kg/s methane, and 0.00907 kg/s ammonia. The wind turbine shows the highest exergy destruction, while calcium looping dominates system cost. The payback period is estimated at 6.47 years. Across the scenario-specific selected optima, optimization increases exergy efficiency up to 47% and net power output up to 4744 kW, the avoided CO 2 -based environmental index up to 0.5998 kg CO 2 /kWh, liquid CO 2 (up to 0.1301 kg/s), gaseous CO 2 (up to 0.7249 kg/s), and ammonia production (up to 0.0262 kg/s), while reducing total specific product cost down to 35.96 $/GJ.