A hybrid centralized-distributed green ammonia system for cost-effective decarbonization of China's nitrogen fertilizer production

Green ammonia system is crucial for decarbonizing the nitrogen fertilizer sector, but its development heavily depends on renewable energy availability. To determine an optimal green ammonia system, this study conducts a comprehensive spatial analysis that incorporates data from 190 existing ammonia plants, high-resolution renewable energy potentials, and cropland distribution across 368 cities in China. The renewable energy allocation model reveals that the uneven distribution of renewable energy resources and the intensive energy consumption of ammonia production (9.81 MWh t−1-NH3) create a 271.81 TWh renewable deficit for retrofitting existing plants, which necessitates the need to deploy distributed green ammonia facilities. The proposed hybrid centralized-distributed system prioritizes renewable energy-rich regions, involving the retrofitting of 135 plants and the deployment of distributed facilities across 186 cities. This system requires 547.46 TWh yr−1 of renewable power, supported by 410.5 GW of solar photovoltaics and 111.0 GW of wind turbines. Compared to solely centralized or distributed systems, the hybrid system achieves the lowest carbon emissions (325.76 kg t−1-NH3) and competitive economic costs (5644.38 CNY t−1-NH3), demonstrating cost-effectiveness within a decade. Our findings highlight the significance of renewable energy-oriented strategies for green ammonia facility deployment, which supports the transition for the nitrogen fertilizer sector.