Innovative ammonia blended natural gas fueled gas turbine − spilt transcritical CO2 cycle combined system based on dual-temperature CO2 turbines: Energy, environmental and economic performance trade-off.

• Novel ammonia blended natural gas GT-STCC based on dual-temperature CO 2 turbines. • Effect of fuel ammonia blending ratio etc. on thermodynamic performance is studied. • Power generation cost and pollutant emission including CO, CO 2 , NO x are evaluated. • Energy, economic, environment performance trade-off via tri-objective optimization. • GT-STCC shows a 2% higher thermal efficiency, a 12.8% lower cost than GT-sCO 2 -tCO 2. In order to solve the temperature interference problem, this paper proposes a novel ammonia-blended natural gas fueled gas turbine − split transcritical CO 2 cycle (GT-STCC) combined system based on dual-temperature CO 2 turbines. One split stream of CO 2 is pumped to CO 2 heater for recovering GT waste heat, while the other stream is pumped to CO 2 regenerator for utilizing high-temperature CO 2 turbine (HCT) waste heat and driving low-temperature CO 2 turbine (LCT). The sensitivity analysis of system thermodynamic performance with respect to fuel ammonia blending ratio, compressor pressure ratio, heat exchanger effectiveness, LCT CO 2 split ratio, CO 2 evaporation pressure is performed under the same total fuel heat input. In addition, the impacts of key operation parameters on power generation cost (PGC) and pollutant emission, including CO, CO 2 , NO x , are clarified. Energy, environmental and economic performance trade-off is achieved through a tri-objective optimization based on genetic algorithm. The results show that a 50 % increase of fuel ammonia molar blending ratio results in a 1.29 % decrease of total thermal efficiency, a 24.66 % decrease of total normalized pollutant emission, and a 35.71 % increase of power generation cost (PGC) for novel GT-STCC. As compressor pressure ratio or heat exchanger effectiveness changes, the normalized CO 2 and NO x emissions show opposite trends. The PGC and total normalized pollutant emission reach minimums under the same LCT CO 2 split ratio of 0.4, while they obtain minimums at different CO 2 evaporating pressures of 250 bar and 350 bar, respectively. The tri-objective optimization shows that the optimal total system thermal efficiency, total pollutant emission and PGC are 54 %, 0.3149 × 10-1 t/MWh and 0.05176 $/kWh, respectively. Compared to the GT − supercritical CO 2 − transcritical CO 2 cascade system, the novel GT-STCC system is a more promising power system due to its simpler configuration, 2 % higher overall thermal efficiency and 12.8 % lower PGC. [ABSTRACT FROM AUTHOR]