Aluminum to the rescue

When it comes ot fuel cells , the challenge of storing the hydrogen has been vexing. Lightweight interstitial hydrides -- compounds in which hydrogen atoms occupy the interstices (spaces) between metal atoms -- have now been proposed as a safe and efficient means for storing hydrogen for fuel cell vehicles. And fuel cells are what many see as the future.

Hydrides using magnesium, sodium and boron have been manufactured, but so far, none have proven practical as a hydrogen repository. An aluminum-based alloy hydride offers a more viable candidate because it has the desired traits of light weight, no toxicity to plants and animals, and absence of volatile gas products except for hydrogen.

Until now, however, only complex aluminum hydrides -- unsuitable for use as a hydrogen storage system -- have been created. In a recent paper in the AIP Publishing journal APL Materials, a joint research group with members from the Japan Atomic Energy Agency (Hyogo, Japan) and Tohoku University (Sendai, Japan) announced that it had achieved the long-sought goal of a simple-structured, aluminum-based interstitial alloy.

“Although its synthesis requires very extreme conditions and its hydrogen content is low, our new compound showed that an aluminum-based alloy hydride is achievable," said Hiroyuki Saitoh, lead author of the APL Materials paper. "Based on what we've learned from this first step, we plan to synthesize similar materials at more moderate conditions -- products that hopefully will prove to be very effective at storing hydrogen."