General Motors reported Monday it has made a breakthrough that brings hydrogen-powered vehicles a bit closer to reality.

The Detroit automaker and its scientific partners said they have found a way to make materials that not only hold more hydrogen, but release it at much lower temperatures than previously achieved.

“We feel we have made progress and we have a growing confidence we will be able to have safe, affordable, practical, hydrogen storage systems in vehicles for our customers,” said Larry Burns, vice president of research and development and strategic planning for GM.

Hydrogen storage is one of the biggest challenges to fuel cells for vehicles, said Sunita Satyapal, hydrogen storage team leader for the U.S. Department of Energy’s hydrogen programs.

GM is working with Hughes Research Laboratories in Malibu, California, to create new materials for storing hydrogen fuel, and is working with the Sandia National Laboratories in Livermore, California, to develop and test fuel tanks to hold the new materials and extract hydrogen from them.

While hydrogen weighs a third as much as gasoline providing the same energy, it takes up at least four times as much space, said James Spearot, director of the Chemical and Environmental Sciences Laboratory at the General Motors Research and Development Center.

“The molecules just don’t want to be in the same space with each other,” he said. So to drive the same distance, either cars would need a hydrogen tank much larger than current gas tanks, or scientists would have to find a way to increase density.

GM would like to keep the configuration of conventional gas vehicles rather than having a much larger tank, although the reality will probably be a mixture of both options, said Mr. Spearot.

Concept carThe Sequel, a GM concept fuel-cell car presented at the Detroit Auto Show in January, has been designed with three tanks totaling twice the size of a normal gas tank. It has a 300-mile range. GM is committed to having the Sequel drivable by the end of this year, said Mr. Burns. The automaker’s goal is to have hydrogen vehicles on sale by 2010.

Researchers say they are “destabilizing” complex metal hydrides—metal alloys that release hydrogen when heated—by blending them with other materials. The solid, powdery material is heated, releasing hydrogen to be used as fuel. The other elements remain in the tank. When hydrogen is added at a refueling station, the reaction reverses, and the material is re-formed.

Sodium alanate hydrides, the new class of complex metal hydrides that GM and Hughes created, have come closest to achieving industry goals for fuel cells, but still fall short, said GM. Researchers working on the GM-Sandia project are using sodium alanate as a surrogate for heat-management testing, while waiting for better materials to be developed, said GM.

Theoretically, metal hydrides can store more hydrogen per volume than pure hydrogen. To penetrate the market, they will need to be able to hold 5 to 6 percent hydrogen. Hydrides can currently store between 5 and 9 percent, but most still require temperatures of between 525° and 1,650° F. With destabilization, however, some can reach 5 percent with temperatures and pressures possible in automobiles. Magnesium hydride, for instance, requires only 80° when it is destabilized, and can store 5 percent hydrogen.

But Mr. Spearot said “we’re still a long way from what’s needed,” and added that GM is still open to other options for storing hydrogen on a vehicle, including liquid hydrogen, compressed gaseous hydrogen, nano-structure absorption, conventional metal hydrides, and light element systems.

Even if the answer turns out to be complex metal hydrides, serious challenges remain. Researchers are still working to get those hydrides to release more hydrogen at lower temperatures, and to avoid using more than 5 percent of the energy just to raise the heat to produce the energy. The system also must cool the tank when refueling to allow the hydrogen to bond with the other elements, and to recharge the hydride with hydrogen more quickly.

And refueling must be made easy, said Mr. Spearot, so customers are as comfortable refueling with hydrogen as they are with gasoline.

Outside the car, there are other barriers. Among those are the cost of hydrogen production and distribution; the cost, size, weight and durability of fuel-cell propulsion systems; a lack of codes and standards; safety issues; and education.

“Do we know we have the answer to the world’s long-term storage? No,” allowed Mr. Burns. “But we’re on our way to understanding hydrogen tank storage solutions. We’re at an exciting point right now.”