Review of Solid State Hydrogen Storage Methods Adopting Different Kinds of Novel Materials

Table 1

Properties of hydrogen compared to other fuels. Data adapted from [46].

Property	Units	Hydrogen	Methane	Propane	Methanol	Ethanol	Gasoline
Chemical formula		H2	CH4	C3H8	CH3OH	C2H5OH	( = 4–12)
Molecular weight (a, b)		2.02	16.04	44.1	32.04	46.07	100–105
Density, NTP (3, a, c)	kg/m³	0.0838	0.668	1.87	791	789	751
	lb/ft³	0.00523	0.0417	0.116	49.4	49.3	46.9
Viscosity, NTP (3, a, b)	g/cm-sec	8.81E − 5	1.10E − 4	8.012E − 5	9.18E − 3	0.0119	0.0037–0.0044
	lb/ft-sec	5.92E − 6	7.41E − 6	5.384E − 6	6.17E − 4	7.99E − 4	2.486E − 4–2.957E − 4
Normal boiling point (a, b)	°C	−253	−162	−42.1	64.5	78.5	27–225
	°F	−423	−259	−43.8	148	173.3	80–437
Vapor specific gravity, NTP (3, a, d)	Air = 1	0.0696	0.555	1.55	N/A	N/A	3.66
Flash point (b, d)	°C	<−253	−188	−104	11	13	−43
	°F	<−423	−306	−155	52	55	−45
Flammability range in air (c, b, d)	vol%	4.0–75.0	5.0–15.0	2.1–10.1	6.7–36.0	4.3–19.0	1.4–7.6
Autoignition temperature (b, d)	°C	585	540	490	385	423	230–480
	°F	1085	1003	914	723	793	450–900
Maximum flame velocity in air (2, c)	m/s	2.83	0.45	0.46	N/A	N/A	N/A
	ft/s	9.28	1.48	1.52