Metastable Metal Hydrides for Hydrogen Storage

Table 1

Comparison of hydride—fuel cell system (AlH₃ + 50 kW fuel cell operating at 50% efficiency and assuming an additional 50% energy reduction to account for the fuel cell system weight) with conventional battery systems showing the specific energy and energy density.

Energy source	Specific energy (MJ/kg)	Energy density (MJ/L)
700 bar hydrogen tank [17]	6.2	3.2
350 bar hydrogen tank [17]	6.6	2.1
AlH3/fuel cell	3.1	4.3
Li polymer	0.72	1.1
Ni-Metal hydride	0.29	0.36
Ni-Cd	0.18	0.36
Pb-acid	0.11	0.14