Transition pathway from blue to green ammonia production: Comparative insight into technoeconomic, environmental, and policy framework

Ammonia is increasingly recognized as a viable hydrogen carrier due to its high hydrogen density, carbon-free combustion, and mature infrastructure. However, conventional ammonia production is energy-intensive and carbon-intensive, prompting a transition toward low-carbon alternatives. This review evaluates recent advancements (2020–2025) in blue, green, and hybrid ammonia production technologies, including gas switching reforming (GSR), renewable-powered electrolysis, and emerging electrochemical methods. Comparative technoeconomic and life cycle assessments reveal that blue ammonia remains economically attractive, though dependent on carbon capture efficiency and methane leakage control. Green ammonia offers superior environmental performance but is constrained by high costs and renewable intermittency. Hybrid systems provide a balanced pathway, integrating the strengths of both approaches. The study highlights the role of technology integration, regional energy strategies, and supportive policies in enabling a scalable transition toward sustainable ammonia production.