Process Simulation and Techno-Economic Assessment of Hydrogen Liquefaction Plants with Integrated Ortho-Para Conversion

Hydrogen liquefaction plants are a key component of liquid hydrogen supply chains. However, to meet future hydrogen demands for climate-friendly mobility, a significant scale-up is necessary. This study aims to provide a deeper understanding of hydrogen liquefaction plants by presenting process simulations of smaller- and large-scale plants using UniSim® Design. The process simulations accurately integrate the conversion of orthohydrogen to parahydrogen taking place continuously within the heat exchanger channels, along with the associated conversion heat. A techno-economic analysis evaluates the cost-effectiveness and energy efficiency of the processes. The results, which are validated against literature data, indicate that CAPEX and OPEX contribute equally to the overall liquefaction costs, with heat exchangers and compressors identified as the main cost drivers. A significant reduction in specific CAPEX and specific energy consumption is observed with increasing plant size, influenced by economy of scale and precooling technology. By integrating process simulation with techno-economic evaluation, this study provides valuable insights into the performance and specific costs of hydrogen liquefaction plants.