Optimizing integrated hydrogen liquefaction with LNG cold energy: A thermoeconomic assessment, comparative analysis, and feasibility study with emphasis on composite curves and uncertainty scrutiny

Nowadays, hydrogen liquefaction is one of the promising methods to reduce hydrogen transportation and storage problems. High energy consumption is a limiting factor in the increasing development of hydrogen liquefaction plants. Therefore, it is necessary to develop methodological structures for the investigation of the hydrogen liquefaction pathways with the aim of energy saving. The current paper aims to develop, feasibility, and optimize a new pathway for a large-scale hydrogen liquefaction plant enhanced with cold energy derived from liquefied natural gas (LNG) cold energy. The offered pathway is based on four mixed refrigeration units (i.e., pre-cooling, cooling, LNG based-cooling, and liquefaction units) designed for a capacity of 50 tons per day. To more accurately investigate and identify the heat cascade and cost variances, composite curve and uncertainty analyzes have been developed. According to the outcomes, control of LNG cold energy is an important factor in the optimization of the hydrogen liquefaction pathway, which can decline the specific energy consumption of the optimized pathway by 28.5 % compared to the non-optimized pathway. Further, under optimized pathway for hydrogen liquefaction, the unit production cost, CO2 emission rate, and the specific energy consumption for CO2 avoided decreased by around 4.5 %, 27 %, and 22.5 %, respectively.