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UCLA Finds Nanoscale Secrets to Hydrogen Car Storage

by Editor1 last modified February 28, 2008 - 16:50

Researchers at the UCLA Henry Samueli School of Engineering and Applied Science are turning to molecular simulations to tackle a long-standing obstacle of making hydrogen-powered cars that can drive beyond 100-200 miles. The group conducted computational analysis for crafting practical ways to design hydrogen fuel storage.

UCLA Finds Nanoscale Secrets to Hydrogen Car Storage

A recent hydrogen concept car from Mercedes

The UCLA study appeared in late February on the website for the Proceedings of the National Academy of Sciences (PNAS).

The work builds on and drills down into some long-held knowledge about hydrogen chemistry. A decade ago, scientists found that adding titanium in a small amount to sodium alanate will lower the temperature of hydrogen released from the material, as well as enable easy refueling by supporting the storage of high density hydrogen at reasonable pressures and temperatures. But, just how did titanium make this possible?

“Nobody really understood what the titanium did. The chemical processes and the mechanisms were really a mystery,” said Vidvuds Ozolins, Associate Professor of Material Science and Engineering, a member of the California NanoSystems Institute, and lead author of the study.

Ozolins’ group at UCLA researched to find out just how titanium was working in this setting, using models for physics, chemistry and quantum mechanics. Their computation gave the researchers information that would have been very difficult to obtain experimentally.

As a result: The Ozolins’ group work suggests that titanium facilitates a reaction mechanism essential for the extraction of hydrogen, and that reaction involves diffusion of aluminum ions within the bulk of the hydride. Thus, the group went on to conclude, titanium facilitates processes in the material that are essential for turning on this mechanism and extracting hydrogen at lower temperatures.

“Sodium alanate in itself is a prototypical complex hydride with a reasonable storage density and very good kinetics. Hydrogen goes in and comes out quickly but it wouldn’t be practical for a car simply because it doesn’t contain enough hydrogen. So that’s why we are so interested in understanding how the hydrogen comes out, what happens exactly and how we can take this to other materials,” said Ozolins.

This method and this knowledge can now be used to analyze other materials that would make for better storage systems than sodium alanate, one team member said, noting that the work is still at the “fundamental end of the study.”

Ozolins and other team members are also members of the California NanoSystems Institute.