When it comes to developing an economy based on hydrogen instead of fossil fuels, one of the key issues is how to store the gas in vehicles. Playing David next to Goliath national labs, researchers at a small university are looking at using ultrathin glass spheres as a storage device that's cheaper, more reliable and safer than metal tanks.
The research team is getting started thanks to a $2 million Energy Department grant that's part of President Bush's FreedomCar program — a $1.2 billion initiative to develop cars that run on hydrogen-powered fuel cells.
The miniature glass spheres, known as microspheres, "are a much safer method for transporting hydrogen," says Jim Shelby, project leader and professor of ceramic engineering at Alfred University in Alfred, N.Y.
"Each tiny microsphere acts as its own pressure vessel. In an accident, they would not break and release a large quantity of hydrogen, as would the rupture of a big tank of gas," he adds. Instead, the spheres would just spill onto the ground, some possibly breaking into beads that would release minute amounts of hydrogen.
Super-strength glass
It sounds counterintuitive -- a flammable gas stored in glass? -- but this is no ordinary glass. Each microsphere is smaller than a grain of table salt, and that's exactly what makes it so strong.
"Glass normally breaks due to the presence of very small flaws in the surface," says Shelby. Glass bottles and windows break because they are larger than the flaws, which are about one micrometer long. But since the wall thickness of the spheres is less than that, Shelby notes, "no such flaws can exist in the microspheres."
"The strength is about 100 times greater than that of normal glass" and even stronger than the optical fibers used in telecommunications, Shelby adds. "You can crush them if you pound on them with a hammer with them lying on a steel plate, but that's about it."
At 50 micrometers in diameter and with a wall that's less than a micrometer thick, each microsphere contains a minute amount of hydrogen. But trillions can be bunched together to make for a sizeable storage system that weighs much less than a traditional heavy steel tank.
Shelby envisions a day when drivers fill up cars with microspheres the way they pump gasoline. "The refueling process would be in two steps. First, a vacuum would suck the used spheres out and send them to a tank for refilling. New, filled spheres would then be pumped in from a different tank," he says. "The consumer would not see much difference from today's system."
Made of sand, the microspheres are very light, inexpensive, easily recycled "and can be repeatedly filled and refilled without degradation," he adds.
What's next
Technical hurdles with the project include finding a reliable way to release the hydrogen on demand. And that's where the Alfred University researchers came up with a breakthrough: using light to trigger that reaction.
By treating the spheres with various chemicals, the researchers use light to release the hydrogen in a second or two. They can also adjust the light's intensity to control the rate of flow.
"So starting the car would turn on the light at a level to begin production of electricity by a hydrogen fuel cell," says Shelby. "Acceleration would be done by just increasing the intensity of the light to provide more hydrogen to the fuel cell."
Perfecting that technique is where much of the research will focus and Shelby acknowledges that it will be "tricky."
Other challenges include making microspheres that are similar to, but more specialized, than existing commercial ones used primarily in medicine. And Savannah River Laboratory, a federal agency, will help with the process of filling the spheres with hydrogen.
Within four years, the researchers hope to have a "tabletop" device that can drive a fuel cell and show that the concept is practical.
'Politics of hydrogen'
The researchers realize they are small players in the hydrogen storage field — in fact their grant is a fraction of the $150 million doled out by the Energy Department for hydrogen storage research.
They also feel that their greatest challenge might be in overcoming what they see as institutional bias.
"In many ways, the key obstacles are not in the technology but in the politics of hydrogen," says Shelby. The large national labs are exploring more conventional storage devices, he notes, and "they have tens of millions of dollars of support each year."
"Since large research groups have been working in those areas for many years, they have established themselves as the 'viable' technologies," he adds. And that makes it hard for other ideas, like the spheres, "to get the attention of the vehicle manufacturers and funding agencies."
Still, Shelby sounds confident that, on its merits at least, the technology should prevail. "We believe that this will prove to be cheaper, more reliable and safer than the other methods," he says.