Cold energy circulation in liquid hydrogen supply: Bridging liquefaction and regasification

This study proposes a novel cold energy circulation system using liquid nitrogen (LN2) as an energy carrier in liquid hydrogen (LH2) supply chain. The conventional LH2 supply chain faces significant bottlenecks due to substantial energy consumption during liquefaction and cold energy waste during regasification. In the proposed system, an air separation unit is integrated into the LH2 regasification process to utilize the LH2 cold energy for separating air into high-purity nitrogen and oxygen and for liquefying nitrogen. LN2 is transported to the liquefaction stage via empty LH2 ships and used as a refrigerant for H2 liquefaction. This cold energy circulation reduces energy consumption and carbon emissions in the overall LH2 supply chain by 9.7 % and 18.3 %, respectively. Although air separation requires additional equipment and power, the energy savings from H2 liquefaction and the revenue from N2 and O2 sales reduce the annual costs by approximately 38.2 % compared to the conventional LH2 supply chain. These results demonstrate that the proposed cold energy circulation system can significantly boost the sustainability of the LH2 supply chain.