Despite its necessity, the establishment of an internationally integrated hydrogen supply network presents multiple challenges at the national level. First, the wide array of renewable hydrogen production technologies, coupled with their generally low technology readiness levels (TRLs), creates uncertainty regarding their scalability and long-term viability. Second, hydrogen transportation technologies exhibit substantial diversity, each offering distinct economic and environmental characteristics. This diversity complicates the quantitative evaluation of their respective advantages. Third, the large number of potential hydrogen-exporting countries introduces additional complexity, as each offers different trade-offs in terms of transportation distance, market price, and global warming potential (GWP). Finally, the ability to ensure a cost-effective and sustainable hydrogen supply through a robust supply chain is essential for supporting industrial applications and progressing toward climate goals. To overcome these barriers, a simulation-based system-level optimization approach is needed to identify optimal hydrogen import strategies.
This study implements a system-level optimization of the hydrogen supply chain based on liquid organic hydrogen carriers (LOHCs), focusing on trade-offs between economic viability and environmental sustainability. Although chemical storage technologies generally exhibit lower TRLs and more complex conditioning requirements compared to physical storage options (e.g., high-pressure or liquefied hydrogen), they offer advantages such as simpler liquefaction and reduced transportation energy requirements. According to the International Energy Agency (IEA), while physical storage methods are expected to dominate the short term due to their technical maturity, chemical carriers are projected to gain preference in the long term owing to their practical benefits in storage and transport. In particular, LOHCs are considered promising due to their compatibility with existing petrochemical infrastructure and their high recyclability.
The optimization framework developed in this study follows a three-pronged approach. First, extensive data collection was conducted across hydrogen production and transportation stages. Economic and environmental indicators were derived from literature or through direct process simulations. LOHC-specific processes were modeled individually to reflect the unique characteristics of each carrier, followed by techno-economic analysis (TEA) and life cycle assessment (LCA) to obtain quantitative metrics. Second, mathematical modeling was employed to simulate the hydrogen supply chain, incorporating key parameters such as renewable energy availability and carbon pricing. The optimization objective was to minimize the total cost, encompassing both economic expenditures and CO2 emissions. Third, scenario-based analysis was used to generate insights under varying assumptions, such as target GWP thresholds for clean hydrogen certification and levels of low-carbon hydrogen adoption. This enabled the identification of robust hydrogen import strategies aligned with current and projected policy landscapes.
To reflect global uncertainties, three scenarios were analyzed. The first scenario examined the influence of grid electricity GWP on clean hydrogen certification standards. For instance, the European Union's Renewable Energy Directive II (RED II) and Taxonomy Regulation set a 3.38 kgCO2e/kg H2 threshold for renewable and low-carbon hydrogen on a well-to-wheel basis, while the U.S. Inflation Reduction Act (IRA) and Clean Hydrogen Production Standard (CHPS) stipulate a 4.00 kgCO2e/kg H2 limit on a well-to-gate basis. This scenario assessed the required GWP levels of grid electricity needed to comply with certification standards and evaluated the impact of electricity decarbonization on hydrogen cost and environmental performance. The second scenario addressed the impact of varying hydrogen import reliance limits. Diversifying hydrogen import sources enhances supply chain resilience and energy security. This scenario analyzed the relationship between import diversification, hydrogen price, and GWP outcomes, offering insights into how dependence on foreign hydrogen sources affects overall system performance. The third scenario evaluated the effect of carbon allowance price fluctuations. With carbon prices in the EU ETS averaging $79.5/ton from 2021 to 2023 and projections indicating increases to $130–160/ton by 2030 and potentially $500/ton by 2050, this scenario explored how carbon pricing influences the economic feasibility of hydrogen. The results highlight the importance of policy support in making hydrogen a competitive energy option and quantify the impact of carbon costs on supply chain configurations. Overall, this study presents critical insights for formulating hydrogen import strategies that balance economic and environmental objectives under diverse future conditions, thereby supporting global carbon neutrality goals and the transition to sustainable energy systems.