Two glass scientists from Alfred University’s School of Engineering are in the fast lane with a $2 million federal Department of Energy grant to develop new technology for a storage system for hydrogen to power a new generation of vehicles.

AU’s team – Dr. James Shelby, the McMahon Professor of Ceramic Engineering, and Dr. Matthew Hall, assistant professor of glass science – received one of only 10 grants awarded nation-wide as part of the $350 million “Freedom Car’ program designed to put hydrogen-powered cars on the road by 2015. The AU proposal was selected for funding from among more than 400 submitted.

Glass? To store hydrogen?

Doesn’t hydrogen have to be stored under high pressure? And doesn’t glass break too easily?

What Shelby and Hall are proposing is a system that would encapsulate hydrogen at 10,000 pounds per square inch (psi) in microspheres, tiny glass beads that have a 50-micron diameter, about that of a human hair, Shelby explained.

Glass microspheres are used for a variety of purposes, including delivering minute amounts of radiation to deeply imbedded malignancies, such as those in the liver. Today, the microspheres are produced in quantity by Mo-Sci Corporation, one of AU’s partners in the Freedom Car research project.

“The glass beads can literally be made for pennies per ounce,” said Shelby, satisfying one goal of the project: creating an inexpensive way to store the hydrogen.

And while people have concerns about glass being fragile, in reality, the tiny beads are very, very strong. “What makes glass break are tiny flaws, microscopic in size, “ said Hall. “But because the microspheres are so small, they rarely have flaws that would cause them to break.”

Shelby noted, “For their size, their strength is enormous.” He pointed out that the beads are about the same size as a grain of sand, and just like walking on the beach doesn’t cause the grains of sand to break, even pounding on the glass beads doesn’t cause them to break. “And even if one of the beads broke, the amount of hydrogen within each is so small that it’s not dangerous,” he added.

Hydrogen – the lightest of all elements and the most plentiful in nature – does need to be stored under pressure and released upon demand, but it is not as dangerous as many people assume, said Shelby. “When people think about hydrogen as a fuel, they think about the explosion of the Hindenburg,” a giant dirigible that exploded as it was attempting to land in Lakehurst, NJ, on May 6, 1937. When heated, hydrogen will explode, but what caused the Hindenburg disaster, NASA research has recently demonstrated, was the highly flammable varnish that coated the airship’s fabric covering.

The glass spheres themselves hold the pressure on the hydrogen at 10,000 psi, Shelby said, thus eliminating the need to contain the hydrogen in a pressurized on-board tank. “We effectively replace the gas tank with something that holds the equivalent of sand,” he said. “If there’s an accident and it ruptures, all it would do is spill. It doesn’t pool under the car the way gasoline does,” noting that pooled gasoline is the major fire risk in accidents. The spilled beads could be safely swept up.

Containing the hydrogren in minute quantities within the glass beads thus meets the second criteria: It’s not just safe, but inherently safer than a gasoline-powered vehicle.
But how to get the high-pressure hydrogen out of the glass beads, and into the fuel cell quickly enough to not just power the car, but to allow it to respond to traffic conditions, accelerating or decelerating as needed?

That’s where the AU solution really shines, so to speak.
Work done by two of Shelby’s recent graduate students, Brian Kenyon, who received his BS degree from AU in 1996 and a master’s in 1998, and who now works for Vesuvius in Pittsburgh, and Douglas Rapp, who received an MS degree in 1999 and completed his Ph.D. degree at Alfred earlier this month, demonstrated that when a light is shined on the microspheres that have been “doped” (chemically treated) with an optical activator (something that reacts to light), the hydrogen is rapidly released. Other than the dopant, the glass that Shelby anticipates using for the beads is essentially the same as that used in making common, everyday bakeware.

The original work that led to the discovery of photo-induced hydrogen diffusion in glass resulted from an Alfred University research project supported by Praxair, Inc., which is one of the leading suppliers of hydrogen for industrial processes. Later work in the same area was supported by the Alfred University Center for Environmental and Energy Research (CEER), which is supported by the federal Environmental Protection Agency.

“The brighter the light, the faster the hydrogen is diffused,” said Shelby. In effect, the light shining on the glass beads causes the dopant to react, opening up the microscopic pores that occur naturally in the glass. The hydrogen, which is under high pressure inside the spheres, will move (diffuse) through the pores to the fuel cell.

The amount of hydrogen available to the fuel cell would also depend on the rate of flow of the beads through the system. Shelby said the tiny, smooth beads actually flow like a liquid, so the rate at which they are exposed to the light could vary depending upon the rate at which they were pumped from the tank into the area of the vehicle where the reaction would occur.

“The hydrogen could remain stored, under pressure, for years, but will diffuse almost immediately if exposed to the light,” said Shelby.

What kind of light that will be and how it will be powered are among the questions still to be answered, said Hall, who admits, “Right now, we’re just using one of those infrared lights like they use at pretzel stands to keep the pretzels warm.”

Another problem that would have to be resolved is how refueling would work. Shelby pointed out that another major advantage of the microspheres is that they are recyclable. What he envisions is pulling into a fueling station, and using a vacuum connection to suck now-empty beads out of the tank for recycling, with another connection to refill the tank with new beads. “I don’t think there would be huge difference to consumers” in the way they fill their tanks now, said Shelby, except for maybe the price. “The beads are cheap. We can literally make them by the ton,” he said.

Hall explained the beads can be made on small scale in the laboratory. Glass frit – the raw materials from which glass is made – is poured into a hot flame. The frit melts nearly instantaneously, and then reforms as it cools into the spheres. The force of the flame propels them into a collection tube, where they collect as they cool.

The hollow beads can then be placed in a pressurized chamber filled with hydrogen. Because the pressure inside the chamber is higher than the pressure inside the beads, the hydrogen glass will flow into the beads, to be sealed there when the pressure inside the chamber is reduced.

Developing a method of filling the beads easily, quickly and cheaply is one of the questions that will be addressed in conjunction with another of AU’s research partners in the grant, the Savannah River Lab, which Shelby said has the largest facility for high-pressure hydrogen research in the country.

While the Freedom Car program aims to develop a concept by 2010 and have cars on the road by 2015, Shelby anticipates it may actually be longer than that before hydrogen-powered cars are commonplace.

Don’t anticipate the order, “Gentlemen, turn on your lights,” anytime soon.