Objective Ammonia is acknowledged as an efficient hydrogen storage medium, having the potential of being a substitute for fossil fuels in achieving the vision of a "carbon-free future". Due to its stable liquid-state attributes in storage and transport, establishing a transmission system integrating green ammonia and product oil using in-service product oil pipelines is of important significance for fostering a green ammonia industry chain.

Methods This paper began with a comprehensive introduction to background information, including the production capacity distribution of green ammonia in China, the pros and cons of different transportation modes, and the potentiality of integrating liquid ammonia transmission into in-service product oil pipelines. Then the adaptability of the system in integrating liquid ammonia transmission was analyzed from six dimensions: properties of transmission mediums, long-distance pipeline structure, pipes and equipment, pipeline transmission technology, hydraulic calculation method, and safety considerations related to operational pressure and fow rates. Considering the coupling characteristics of green ammonia and product oil during transportation, a conceptual plan was outlined for establishing green ammonia and product oil integrated transmission systems based on the supply and demand patterns of "westeast ammonia transmission" and "north-south ammonia transmission".

Results As the production capacity of green ammonia continuously expands, pipelines have emerged as the preferred mode for long-distance transportation. Moreover, given the underutilized transmission capacity of existing product oil pipelines, notable potential exists in integrating liquid ammonia transmission into these pipelines to enhance economic benefits. Theoretically, current product oil pipelines bear striking resemblance to existing long-distance liquid ammonia pipeline systems, so they are capable of meeting specific requirements for liquid ammonia transport when offered with technological or equipment upgrades. Therefore, under the premise of implementing rational pressure and flow rate control strategies, the system integrating liquid ammonia transmission into operational product oil pipelines exhibits robust adaptability, necessitating further experimental validation of their feasibility. This paper envisioned the potential of these integrated systems across four key aspects: planning for green ammonia and product oil integrated transmission systems, optimization through collaboration of multiple transportation modes, defining operational boundaries for liquid ammonia pipeline transmission, and optimization of pipeline transmission batches.

Conclusion The study outcomes can serve as a valuable reference for promoting the healthy development of the green ammonia industry and enhancing the safety and economic efficiency of green ammonia and product oil integrated transmission systems.