PORTLAND, Ore. In order for hydrogen-powered automobiles to succeed, the fuel needs to be pumped into tanks as easily as gasoline--and without the threat of Hindenburg-like disasters.
Sandia National Laboratories recently suggested an alternative technology for synthesizing carbon-based fuels so that the current U.S. fuel distribution system can be used. Now, Ford Motor Co. has emerged with an autocatalytic reaction scheme involving three hydrides that could someday enable hydrogen to be pumped into tanks as easily as gasoline.
The technique, called a ternary-hydride autocatalytic reaction, stores hydrogen in a solid semi-metal--a compound of magnesium, lithium and hydrogen--that can quickly be absorbed and released. Others have already suggested using metal hydrides for hydrogen storage since the reaction is well-known and reversible. Until now, the temperatures and pressures required to release the hydrogen were too high to be feasible.
The trick to achieving low-temperature and pressure reactions, discovered by a Ford research team led by Jun Yang, in cooperation with researchers at the University of California-Los Angeles, is to combine three different semi-metals--lithium amide, lithium borohydride, and magnesium hydride. By mixing the ternary hydride in the ration of 2:1:1, the researchers demonstrated the release of hydrogen at 302 degrees F at pressures low enough to make it feasible for use in automobiles.
The autocatalytic reaction mechanism was shown to be fast enough to enable hydrogen to be pumped into an automobile's "solid" tank at speeds comparable to gasoline being pumped into today's liquid tanks. Also, no undesirable byproducts such as ammonia were released. Such byproducts are common when hydrogen is used with one or two hydrides.
The ternary hydrides enabled relatively low-temperature and low-pressure absorption as well as release of hydrogen by virtue of an autocatalytic reaction that begins like a single hydride reaction. It was then successively taken up by two other semi-metals to speed the sequence without excess heat or pressure. The process also eliminated the byproducts normally associated with the storage of hydrogen in a metal hydride, the Ford researchers claimed.