Environmentally friendly hydrogen gas fueled vehicles can dramatically reduce greenhouse gas emissions and lessen the countrys dependence on sources of fossil fuel. Though several hydrogen vehicles exist on the market today, there is still much room for improvement in the way that hydrogen is stored on-board the vehicle. With current technologies, hydrogen gas storage tanks have to be as large as or larger than the trunk of a car to carry enough gas to travel only one to two hundred miles.
While liquid hydrogen is denser and takes up less space, it is very expensive and difficult to produce. It also reduces the environmental benefits of hydrogen vehicles. Widespread commercial acceptance of these vehicles will require finding the right material that can store hydrogen gas at high volumetric and gravimetric densities in reasonably sized light-weight fuel tanks.
Researchers at the UCLA Henry Samueli School of Engineering and Applied Science, with the use of molecular dynamics simulations, have solved a decade old mystery that could one day lead to commercially practical designs of storage materials for use in hydrogen gas fueled vehicles. The study appears on the Proceedings of the National Academy of Sciences (PNAS) web site on February 27.
In 1997, it was discovered that adding a small amount of titanium to a well-known metal hydride, sodium alanate, not only lowers the temperature of hydrogen release from the material but also allows for an easy refueling and storage of high density hydrogen at reasonable pressures and temperatures. In fact, the weight percent of stored hydrogen was instantly doubled in comparison with other inexpensive materials.
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.
|Contact: Wileen Wong Kromhout|
University of California - Los Angeles