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| Table 7.5 |
| Comparison of Hydrogen Storage Methods for Fuel Cell Vehicles |
| |
Name |
Storage Temp, ºC |
Storage Pressure, MPa |
Hydrogen by mass, % |
Volume,litre/ kg of H2 |
| 1 |
High pressure cylinder |
Ambient |
35 to 70 |
2 to 4.5 |
40 -70 |
| 2 |
Liquid H2 |
- 252 |
Ambient |
14 |
25 |
| 3 |
Fe-Ti hydride |
- 10 |
2.5 |
< 2 |
36 |
| 4 |
Methanol |
Ambient |
Ambient |
12.5 |
10 |
| 5 |
NaBH4 |
Ambient |
Ambient |
10.58 |
9.5 |
Prototype Fuel Cell Vehicles From the early FCV prototypes such as Necar-1 by DaimlerChrysler, considerable progress has been made in the fuel cell vehicle development. Necar-1 had a 50kW fuel-cell stack with 30 kW propulsion system, hydrogen storage capacity of about 2 kg at 300 bar, maximum speed of 90 km/h and a range of 130 km. Honda FCX vehicle built in 2004 is powered by a fuel cell stack of 86 kW, 4.3 kg of hydrogen is stored at 350 bar. It is a normal size car having 150 km/h maximum speed and 395 km range. The vehicle on US FTP cycle achieved fuel economy of 91.8 km/kg of H2. By the year 2006- 07, through development of more efficient fuel cells and 700 bar cylinder pressure storage systems the range of vehicles exceeding 500 km has been attained. Presently the cost of fuel cells is higher by a factor of 2 to 3 compared to gasoline engines of the same power output. Honda Co. believes that by the year 2018 the FCV could be produced at costs that are commercially viable.
The FCV has varying impact on the CO2 emissions as it depends on the hydrogen generation process.. Obviously, if the hydrogen or methanol is produced from natural gas the CO2 advantage of FCV over the conventional IC engines is not significant. If methanol is produced from natural gas to provide fuel for the fuel cell, the effect on CO2 reduction in fact, is negative. The comparative CO2 emission scenario would again change when the IC engines are fuelled by the renewable fuels like ethanol or biodiesel.
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