Study on the energy efficiency of bioethanol-based liquid hydrogen production process

Abstract A hydrogen liquefaction process combined with bioethanol producing hydrogen process and multistage compressor process is designed, simulated and analyzed. Its specific energy consumption (SEC) and coefficient of performance (COP) are 5.41 kWh/kgLH2 and 22.38 %, respectively, and the functional exergy efficiency is 71.13 % for entire process and 53.61 % for the hydrogen liquefaction process. The systematic relationship among hydrogen liquefaction ratio, SEC, COP and functional exergy efficiency of nitrogen precooling cycle, helium cryogenic cycle and whole process are deduced and analyzed. The results show that the process’s performance improves with the hydrogen liquefaction ratio, and the variation trends of SEC, COP and functional exergy efficiency change significantly. The optimal hydrogen liquefaction ratio is 0.89, and the corresponding SEC is 4.71 kWh/kgLH2, reduced by 12.94 %, the COP and functional exergy efficiency are 25.70 % and 81.70 %, and the general exergy efficiency is 43.60 %.