[Objective] In the context of China’s “Dual-Carbon” goals and the low-carbon transformation of coalfired power generation, this study investigates the economic performance and carbon reduction characteristics of ammonia co-firing in coal-fired power units. The effects of unit capacity, ammonia co-firing ratio, and fuel prices on the incremental cost of electricity and carbon emission reduction are analyzed to provide theoretical support and data references for low-carbon retrofits of coal-fired power plants and the application of green ammonia. 

[Methods] Coal-fired power units with capacities of 300 MW, 600 MW, and 1 000 MW were selected as the research objects. An incremental cost of electricity model was established based on the concept of the Levelized Cost of Electricity (LCOE). The incremental electricity generation costs under different coal prices, ammonia prices, and ammonia cofiring ratios were calculated. In addition, annual coal consumption and annual CO₂ emission reductions were estimated using unit coal consumption rates, the calorific value relationship between coal and ammonia, and the CO₂ emission factor of standard coal. A comparative analysis of the economic and environmental performance of different unit capacities was then conducted. 

[Results] The results indicate that the incremental cost of electricity is mainly influenced by the ammonia co-firing ratio and ammonia fuel price, and increases approximately linearly with the co-firing ratio. Higher ammonia prices significantly increase power generation costs, whereas higher coal prices reduce the fuel price gap between coal and ammonia, thereby lowering the incremental electricity cost. Compared with the 300 MW and 600 MW units, the 1 000 MW unit exhibits lower incremental electricity costs and superior economic performance under identical operating conditions due to its lower coal consumption rate and higher generation efficiency. In terms of carbon reduction, annual coal consumption decreases substantially and annual CO₂ emission reductions increase significantly with increasing ammonia co-firing ratios. The 1 000 MW unit achieves the largest reduction, reaching 1.0693 million tons of CO₂ annually at a 30% ammonia co-firing ratio. 

[Conclusion] An economic assessment model incorporating four dimensions—coal price, ammonia price, unit capacity, and ammonia co-firing ratio—was established based on the actual coal price index of Caofeidian in April 2026 and the market pricing ranges of green ammonia and gray ammonia. Ammonia co-firing can effectively reduce coal consumption and CO₂ emissions, representing a promising pathway for the low-carbon transformation of coalfired power generation. Large-capacity, high-parameter units demonstrate superior economic and carbon reduction performance and are therefore more suitable for future large-scale ammonia co-firing applications. However, the high cost of ammonia remains a major barrier to commercialization. Future development should focus on low-cost green ammonia production technologies, carbon trading mechanisms, and low-carbon subsidy policies to further enhance the economic viability and engineering application prospects of ammonia co-firing technology.