Established Methods Based on Compression and Cryogenics - Hydrogen Generation, Storage, and Utilization - page 74

5

Established Methods Based on
Compression and Cryogenics

5.1 BASIC ISSUES ABOUT HYDROGEN STORAGE

Hydrogen storage is one of the major challenges in the development of
hydrogen as a fuel for widespread applications. In this chapter, we will cover
traditional or well-established techniques for hydrogen storage based on high
pressure compression or low temperature liquefaction. Other newer methods
under research and development will be covered in Chapters 6 and 7. We
will first introduce energy content for fuels.
The energy stored in hydrogen or other fuels can be expressed either on
a weight basis (mass energy density or gravimetric capacity) or on a volume
basis (volumetric energy density or volumetric capacity). When hydrogen
reacts with oxygen, water (vapor or liquid) is formed and energy is released,

1
2

H + O = H O ∆ H = 241 826 . kJ mol ⋅

− 1

( lower heating value ) .

(5.1)

2 2 2

Thus, if 1 mol of hydrogen is burned with 100% energy conversion effi-
ciency, 241.826 kJ of energy should be released. Since the molar mass of
hydrogen is M = 2.02 × 10 −3 kg·mol −1 , the mass energy density of pure
hydrogen is

∆ H
M

ρ M

0

= = 119 716 . MJ kg ⋅

− 1

.

(5.2)