Low carbon pathway and life cycle assessment of ammonia co-firing in coal power plants under the context of carbon neutrality

Abstract

The utilization of ammonia as a partial substitute for coal has garnered considerable attention as a technology for direct reduction of CO2 emissions in power plants. This study has established the model of ammonia co-firing in coal-fired power plants (CFPP), encompassing the whole industrial chain from production to transportation and power generation. The assessment focuses on the economic aspects of ammonia co-firing, with a specific emphasis on the opportunities for harnessing abandoned wind and solar resources, and further considers the life cycle assessment (LCA) of environmental impacts. The results show that in the case of the CFPP, gray ammonia and green ammonia co-firing systems at 30% proportion yield the levelized cost of electricity (LCOE) of 0.042, 0.074, and 0.110 USD/kWh under low carbon emissions, while 0.086, 0.122, and 0.142 USD/kWh under zero carbon emissions, respectively. Notably, when low-cost green electricity derived from abandoned wind and solar resources is utilized for green ammonia co-firing systems, the feasibility of the approach significantly improves. In regions with high carbon taxes or low cost renewable power, the LCOE of low-cost green ammonia co-firing systems will be lower than that of CFPP equipped with carbon capture and storage (CCS) unit, which may be realized in developed countries in the future. By 2030, in areas with the carbon tax price above 83.76 USD/tCO2 under low carbon emissions or the coal price above 165.25 USD/t under zero carbon emissions, the LCOE for the low-cost green ammonia co-firing system (30%) will be lower than that of CFPP and CCS-equipped CFPP. Green ammonia co-firing significantly reduces CFPP carbon emissions compared to gray ammonia co-firing, highlighting its substantial potential. At 30% proportion, the whole industrial chain carbon emissions for the system of CFPP co-firing with gray ammonia (GA) increase by 0.302 kg CO2/kWh (40.38%) and the life cycle GWP value increases by 0.380 kg CO2-eq/kWh (46.15%). In contrast, the system of CFPP co-firing with green ammonia (GE) decreases by 0.203 kg CO2/kWh (-27.09%) and 0.173 kg CO2-eq/kWh (-20.98%). These findings provide quantitative information on the economic and environmental benefits of ammonia co-firing to reduce CO2 emissions in CFPP, informing the low-carbon transition of CFPP with ammonia co-firing technology.