News Date: July 21, 2005
US Department of Energy Hydrogen Storage Goal May Be Possible
One of the fundamental challenges of using hydrogen as a fuel is the low density of pure hydrogen at normal atmospheric conditions. Therefore, researchers are seeking methods of storage using compression, refrigeration, and/or absorptive storage materials. The goal is to store enough hydrogen onboard that a fuel cell powered vehicle may travel approximately 300 mile between refueling (a standard distance for today’ internal combustion engine automobiles).
Lightweight materials that will soak up large quantities of hydrogen are urgently needed for fuel-cell vehicles, in which electricity is generated directly from the combustion of hydrogen. This would provide a safer method of fuel storage than keeping the hydrogen in pure gaseous form in high-pressure tanks.
Their idea for hydrogen storage is not entirely new. The concept of using nanotubes was advanced by Michael Heben of the National Renewable Energy Laboratory in Colorado in 1997 but further testing fell short of the goals for hydrogen storage. This led John Tse and his colleagues to critically examine the method of analysis.
The research team found that if they used quantum mechanics in the analysis of hydrogen storage they could model the complex interactions of atoms more accurately. Their calculations reveal that the DOE target — hydrogen storage capacity of 6.5 weight per cent (wt%) — can be attained in graphitic nanostructures at a temperature of about -23 °C and an applied pressure of 10 MPa (100 atmospheres). These, they say, are acceptable conditions for practical hydrogen storage.
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