2021-01 PRESLHY_ChapterLH2-v4

The interest in hydrogen as a clean fuel and energy carrier of the future has grown in many
countries and initiated comprehensive research, development, and demonstration activities with
the main objective of the transition from a fossil towards a CO2 emission lean energy structure
as the ultimate goal.
Hydrogen represents an energy carrier with high energy content and a clean, environmentally
benign source of energy to the end-user. The volume-related energy content of gaseous
hydrogen, however, is comparatively small. For various applications of hydrogen where
volume is an essential issue, it is necessary to liquefy the hydrogen for the sake of volume
reduction. But there are also other situations where the liquid state represents a reasonable and
economic solution for storage and distribution of large amounts of hydrogen depending on the
end-user’s requirements. Furthermore liquid hydrogen has the advantage of extreme
cleanliness making it appropriate in many industrial applications. Major drawback is the
enormous energy input required to liquefy the hydrogen gas, which has a significant impact on
the economy of handling LH2.
The hazards associated with the presence and operation of LH2 containing systems are subject
of safety and risk assessments. Essential part of such accident sequence analyses is the
simulation of the physical phenomena which occur in connection with the inadvertent release
of LH2 into the environment by computation models. The behavior of cryogenic pool
propagation and vaporization on either a liquid or a solid ground as well as potential pool
burning is principally well understood. Furthermore state-of-the-art computer models have
been developed and validated against respective experimental data. There are, however, still
open questions which require further efforts to extent the still poor experimental data basis.
The experimental and theoretical investigation of the characteristics of liquid hydrogen, its
favorable and unfavorable properties, as well as the lessons learnt from accidents have led to a
set of codes, standards, regulations, and guidelines, which resulted in a high level of safety
achieved today. This applies to both LH2 production and the methods of mobile or stationary
LH2 storage and transportation/distribution, and its application in both science and industries.