Exergetic efficiency of centralized and decentralized ammonia cracking supply chains in Asia

Ammonia is widely regarded as a promising hydrogen carrier for long-distance transport due to its high volumetric density and well-established global trading infrastructure. Asia is currently facing urgent challenges related to energy security and sustainability, driven by its vast population and rapid economic growth. Therefore, importing clean ammonia has emerged as an important pathway for facilitating the region’s energy transition. After import, ammonia can be cracked using either a centralized or a decentralized strategy. In the former approach, ammonia is cracked at a large scale at the import terminal immediately after unloading, and the produced hydrogen is subsequently transported to end users via pipelines or road transport. In contrast, the decentralized strategy involves transporting ammonia to demand centers prior to cracking. Decentralized cracking can take the form of large-scale systems integrated with local hydrogen networks or major industrial users, or small-scale cracking units such as hydrogen refueling stations. The choice of ammonia cracking strategy is strongly influenced by the distribution of industrial hydrogen demand and plays a critical role in determining the overall supply chain performance. However, research on the selection of ammonia cracking strategies in the Asian context remains very limited. Focusing on Asian countries where ammonia cracking projects have already been proposed, this study examines five representative economies: China, Japan, South Korea, Singapore, and Thailand. CO2e emission maps are used to identify clusters of industrial activity in each country, which are further employed as proxies for hydrogen demand centers with significant decarbonization potential. Based on the spatial distribution of these demand centers, a set of configurations is constructed using a modular black box framework. Each module is then parameterized based on energy consumption data collected from existing literature and industry reports. On this basis, the energy consumption across different stages of the supply chain is evaluated, and the exergetic efficiency of the system is calculated. By incorporating the spatial structure of industrial activities in Asia into the framework, this study provides an exergy-based perspective for the design of ammonia supply chains.