Johnnny_B_Good (5/9/00)
Copyright 2000 Gannett Company, Inc.He is investigating the use of carbon structures called nanotubes as a storage system for fuel cells in a hydrogen-powered car.
Nanotubes are small, at least 50,000 times thinner than a human hair. But if they can be developed for storage, nanotubes will play a significant role in improving hydrogen-powered vehicles -- virtually pollution-free cars that run on inexpensive, renewable fuel.
+These kinds of structures are the future,+ says Gennett, who has been on a two-year sabbatical from RIT. +For more powerful computers or for fibers that have new characteristics, the way to go is smaller.+
Many scientists see almost magical properties in nanotubes. But some are cautious about uses.
Mildred Dresselhaus, a Massachusetts Institute of Technology professor of electrical engineering and physics, calls the concept of using nanotubes for hydrogen storage promising and unique.
+There is potential, but it's too early to know,+ she says. +The birthday of nanotubes is 1991, when they were first discovered. They are not even 10 years old. We don't have many important or more sophisticated applications of other discoveries in that time scale. But nanotubes offer exciting possibilities.+
The U.S. government is a believer. During his sabbatical, Gennett has been a member of an eight-person team of scientists and engineers at the National Renewable Energy Laboratory in Golden, Colo., one of the nation's top labs in basic energy research.
The lab team recently was awarded provisional patents for the purification of nanotubes and for hydrogen storage in nanotubes. The team also won an $ 850,000 research grant.
The Department of Energy's Hydrogen Technical Advisory Panel cited the team this year for the success of its research.
Gennett, who has taught at RIT since 1990, will return to Rochester this summer. He plans to continue his research on nanotubes by investigating the use of different materials to form nanotubes or mix with carbon nanotubes.
He will be working in one of the hottest fields of basic research: nanotechnology.
As a word fragment, +nano+ means a billionth. Thus, a nanometer is a billionth of a meter. But nanotechnology has come to mean the manipulation of individual atoms and molecules to build structures.
+The potential for nanotubes is quite high,+ says Michael Heben, a senior scientist at the energy lab in Colorado and the team's director. +No material known to man behaves in the manner of nanotubes. That's why NASA, the automakers and a lot of people are interested in them.+
Scientists have shown, for example, that nanotubes can conduct electricity. Some researchers believe that nanotubes could replace silicon chips in computers, leading to the creation of small but powerful computers.
Nanotubes form from the vapor or soot generated by carbon arcs and lasers fired into sheets of graphite one atom thick. The sheets, whose shape resembles chicken wire, spontaneously roll into long cylinders that are a billionth of a meter in diameter.
Nanotubes are stronger than steel -- as much as 100 times as strong, some scientists say.
No other material has a higher strength-to-weight ratio, Heben says.
The high-strength qualities of nanotubes may make them suitable for making cables, transmission lines, airplane skins and body armor, says Daniel Colbert, a faculty fellow at the Center for Nanoscale Science and Technology at Rice University in Houston.
Nanotubes have been used in small, flat-panel displays that could evolve into a new kind of television screen. Their composition also makes nanotubes an efficient light source, Dresselhaus says.
+When Edison invented the light bulb, he ran a current through carbon filament,+ she says. +We could be back to Edison and carbon.+
Researchers at the energy lab have shown that hydrogen can be drawn into carbon nanotubes just as water is drawn into a drinking straw. The nanotubes also can be made to release the hydrogen.
+We don't know if the hydrogen is inside the tubes or trapped in between the tubes,+ Gennett says. +That's why we call this research.+
If the tubes can be produced in the required amount and shaped properly, they could become a lightweight hydrogen sponge, ideal for a storage system or a +gas tank+ in a car.
+It is always difficult working with a material which you can only see with high-powered microscopes,+ Gennett says.
+Our biggest problem is removing the graphite and metals from the nanotubes. When we purify, we are trying to remove anything that is not a nanotube, without destroying the nanotubes. Not as easy at it sounds.+
The process is so difficult that the energy lab is only able to produce a few milligrams of the hydrogen-storing material in a 24-hour period.
The Energy Department's goal is to produce nanotubes that can store an amount of hydrogen that is at least 6.5% of the nanotubes' weight. To power a car about 350 miles under the target conditions, Gennett calculates, the system would need about 98 pounds of nanotubes.
That seems like a big leap from current nanotube production. But the quantity and the quality of nanotubes have increased tenfold in just two years.
And with many working on the production question -- including labs at Cornell University, IBM and Lucent Technologies -- a breakthrough discovery could be made soon, Heben says.
A hydrogen-powered car with a storage system based on nanotubes could be available in 10 years, Heben and Gennett say.
+There is a big push on,+ Heben says. +Usually when there is a push, you uncover the critical stumbling blocks . . . or the technology advances.
+Nanotubes today are where silicon and silicon chips were in 1947. We believe there is great potential. We have a long-term perspective.+
Johnny.