Researchers Identify Aluminum-Hydrogen Complex with Potential for Hydrogen Storage; Analog to Boranes
22 January 2007
Through combined theoretical and experimental study, a team of researchers from Virginia Commonwealth University and Johns Hopkins University has identified a new class of aluminum-hydrogen complexes that are very stable and can potentially be created in bulk quantities, leading to possible application as a hydrogen storage mechanism, among others.
The results of the research, headed jointly by Puru Jena, Ph.D., distinguished professor of physics, and Boggavarapu Kiran, Ph.D., assistant professor of physics, both at Virginia Commonwealth University, and Kit H. Bowen, Ph.D., professor of chemistry at Johns Hopkins University, is reported in the 19 January issue of the journal Science.
The new Al-H molecules are similar in structure and composition to boranes, which are composed of boron and hydrogen atoms. While boranes are known to form a wide array of structures, very little information was known about similar Al-H systems.
The researchers believe that these newly discovered compounds may have applications in hydrogen storage as well as high energetic materials in the future. Scientists can potentially apply this discovery to the design and synthesis of new materials with a chemistry that can be altered at the nano-scale one atom at a time.
The worked reported in Science focuses on one species, Al4H6.
We believe our findings will open a new chapter in Al-H chemistry and may have important applications in materials science. Developing new materials and compounds that meet some of the current technological problems in energy-related fields is always a challenge. Our collaborative work has demonstrated that a synergy between experiment and theory can go a long way in meeting these challenges, particularly in developing novel nano-materials for storing and releasing hydrogen as well as for high-energetic materials applications.
—Puru Jena
The theoretical investigations for this project were conducted by Jena along with B. Kiran, Ph.D., and M. Willis, a graduate student in the physics department at Virginia Commonwealth University. The experimental work was conducted by Bowen with X. Li, A. Grubisic, S.T. Stokes, and J. Cordes, all research scientists in the chemistry department at Johns Hopkins University; and G.F. Ganteför, a professor at the University of Konstanz visiting Bowen's lab at Johns Hopkins University. In addition, R. Burgert and H. Schnöckel, researchers with the Institute of Inorganic Chemistry at the University of Karlsruhe in Germany contributed to this research.
This research was supported by the US Air Force Office of Scientific Research and the US Department of Energy.
Resources:
“Unexpected Stability of Al4H6: A Borane Analog?”; X. Li, A. Grubisic, S. T. Stokes, J. Cordes, G. F. Ganteför, K. H. Bowen, B. Kiran, M. Willis, P. Jena, R. Burgert, H. Schnöckel;; Science 19 January 2007: Vol. 315. no. 5810, pp. 356 - 358 DOI: 10.1126/science.1133767
While this if fascinating, Al4H6 does not sound like a very good gravimetric ratio (5.8%). Could the compound be more impressive from the standpoint of its energy ratio? i.e. stationary applications.
Posted by: Neil | 22 January 2007 at 05:22 PM
Neil,
4.5kg of H2 can propel the Ford Airstream concept car 280 miles. At 5.8% gravimetric ratio, the total weight of the fuel storage would be 4.5kg/.058=77kg, or 170 lbs. At ~36kwh/kg of H2, this is equivalent to 162kwh of energy. This is almost the goal of DOE for H2 storage with gravimetric ratio goal of 6.5%.
By contrast, the EEstor's EESU for a 52kwh storage for a comparable travel range would weigh about 185 kg, or 408 lbs, according to a "revised" gravimetric density of their EESU at 289wh/kg in Technology Review most recent article on EEstor. A Li-ion battery storage at 120wh/kg (A123) would weigh 433kg, or 952 lbs!
Thus, the Ford Airstream can have a PHEV-size battery, a 4.5kg H2 storage tank and small FC stack and still come out lighter than a BEV of comparable payload capacity.
Posted by: Roger Pham | 22 January 2007 at 11:46 PM
how efficient is the production of said material?
what are the conditions required for the release of the hydrogen?
Posted by: coal_burner | 23 January 2007 at 04:06 AM
Roger: Interesting calcs, but I have to wonder, how much would the tank holding this stuff weigh and how much would the stack weigh?
Posted by: Neil | 23 January 2007 at 02:26 PM
There are much better metal hydrides for storing hydrogen. Zinc and Magnesium hold much more hydrogen by weight than aluminum and they are lighter. The charging and discharging of the hydrogen from a metal is usually done by heat. So in as much as weight calculations are necessary, so are calculations for charging and discharging. I believe a more advance alloy of aluminum and magnesium, would hold more promise.
Posted by: Brian Bartel | 25 January 2007 at 06:38 AM