Comprehensive analysis of advanced design for hydrogen liquefaction process with surrounding infrastructure: Focus on techno-economic and environmental perspectives

The work developed and evaluated a new conceptual design of a hydrogen liquefaction process based on the conventional infrastructure for liquid N₂ (LN₂) and liquefied natural gas (LNG). The proposed hydrogen liquefaction processes with open pre-cooling of LNG refrigerant (HLOC) were then compared to the conventional process of N₂-based closed cycle (HNCC, base process) and N₂-based open cycle (HNOC). Utilizing the cold energy of LNG from the open pre-cooling cycle, HLOC requires less other refrigerant flowrate and uses less energy for refrigerant compression and smaller heat exchangers. As a result, HLOC has a lower specific energy consumption (SEC) of 10.4 kWh/kg LH₂, saving 10.8 % and 23.0 % on capital and operating costs, respectively. Finally, HLOC outperforms two other processes with a levelized cost of hydrogen (LCOH) for liquefaction of 2.2 $/kg LH₂ and CO₂ emission of 6.65 kg CO_2eq/kg LH₂. In addition, the exergy performance of HLOC (59.9 %) presented better results than HNCC (46.2 %) and HNOC (55.4 %). To estimate the potential LH₂ production for the Korea context, the proposed and base processes were integrated with the existing ASU infrastructure for LN₂ refrigerant and the existing LNG transmission infrastructure. For regions absent ASU or LNG infrastructure, the newly constructed hydrogen liquefaction process was also evaluated, with additional economic gains expected from the sale credits of the leftover refrigerants. As a result, the work contributes to the planning of future hydrogen liquefaction process while taking into account technological advancements, potential conventional or renewable energy sources, and current industrial status.