Hydrogen Storage Systems Modeling and Analysis

Several different approaches are being pursued to develop on-board hydrogen storage systems for light-duty vehicle applications. The different approaches have different characteristics, such as:

• the thermal energy and temperature of charge and discharge
• kinetics of the physical and chemical process steps involved
• requirements for the materials and energy interfaces between the storage system and the fuel supply system on one hand, and the fuel user on the other

Other storage system design and operating parameters influence the projected system costs as well.

Argonne researchers are developing thermodynamic, kinetic, and engineering models of the various hydrogen storage systems to understand the characteristics of storage systems based on these approaches and to evaluate their potential to meet the DOE targets for on-board applications. The DOE targets for 2015 include a system gravimetric capacity of 1.8 kWh/kg (5.5 wt%) and a system volumetric capacity of 1.3 kWh/L (40 g/L). We then use these models to identify significant component and performance issues, and evaluate alternative system configurations and design and operating parameters.

Some of the automotive hydrogen storage systems we have modeled and analyzed include:

• Compressed gas tanks, for 350-bar (5000 psi) and 700-bar (10,000 psi) service
• Cryo-compressed tanks for storing liquid hydrogen or compressed gaseous hydrogen up to 270 bar (4000 psi)
• Hydrogen storage in metal-organic framework (MOF) materials at 77 K and 70 bar (–196ºC and 1000 psi)
• Systems that require off-board regeneration of the depleted material, such as systems using ammonia boranes, sodium and lithium alanates, and alanes

A schematic drawing of a MOF-177 On-Board Hydrogen Storage System.

January 2010