The quest for a sustainable hydrogen energy economy hinges on reducing the energy consumption associated with hydrogen liquefaction.
A recent study published in the International Journal of Hydrogen Energy sheds light on innovative methods to achieve this goal, focusing on the exergy of liquid hydrogen. Authors M. Lenger, S. Heinke, W. Tegethoff, and J. Köhler have carried out a detailed exergy analysis of the hydrogen liquefaction-regasification chain, presenting promising results that could significantly impact energy consumption in hydrogen production and utilization.
Hydrogen liquefaction traditionally demands substantial energy, often quantified at approximately 40% of hydrogen’s lower heating value (LHV). This high energy consumption poses a significant challenge in creating an energetically efficient hydrogen economy. However, ambiguity in boundary conditions across published data often renders these values unreliable, necessitating a clearer understanding of how to achieve efficient hydrogen liquefaction.
The research highlights two main strategies to decrease energy consumption: improved liquefiers and the utilization of liquid hydrogen exergy. Exergy, defined as the reversible liquefaction work stored in liquid hydrogen, stands at 11.5% of hydrogen’s LHV, which is notably 5.5 times the exergy of liquefied natural gas (LNG) per energy content. By implementing advanced liquefiers with an exergy efficiency of 44%, substantial energy savings can be achieved.
By integrating these improved liquefiers and maximising the exergy utilization processes, the researchers estimate that the net energy consumption for the hydrogen liquefaction-regasification chain could be reduced to an impressive 13-26% of hydrogen’s LHV. This reduction represents a significant leap towards an energetically efficient hydrogen fuel cycle.
