Ethanol plants either are operating, under construction, or planned for several areas in the Midwest. These same areas also have municipal solid waste (MSW) produced daily in an existing...
Energy Tech's Quantum Leap
continuous inhale and exhale cycles-cycles that Georgia Tech researchers call "oxygen pumping." Theoretically, this principle could yield technology for small-scale hydrogen production, which would address the fuel transportation and storage issues that now constrain fuel cells' commercial viability.
The Georgia Tech studies are focused on improving the efficiency of the oxygen-pumping process. "Our progress shows surprising improvements," says Dr. Zhong L. Wang, professor and director of Georgia Tech's Center for Nanoscience and Nanotechnology. By doping iron atoms into the oxides, Georgia Tech researchers have lowered the temperatures at which the rare-earth oxides produce hydrogen, from about 1,700 C to about 400 C. Additionally, researchers have developed techniques that eliminate the need for catalysts in the process-catalysts that are expensive and that degrade with use.
"Our next steps are to try to reduce the temperature more and improve efficiency," Wang says. "For large-scale production, we have to improve the pumping speed by a factor of five." Although this represents a significant research challenge, if successful it could give fuel cells a major boost.
An even bigger boost, however, could come from developments within the fuel cell itself. Toward this end, PlugPower Inc. in Latham, N.Y., together with Albany NanoTech, an R&D arm of the State University of New York, began developing nanostructures and materials for polymer electrolyte membrane fuel cells. The five-year project is aimed at achieving three main goals:
First, nanotechnology could improve the initial and long-term performance of fuel cells by optimizing the nano-scale structure of the electrodes. "If you put the particles down in a predetermined, structured way, you will get higher current densities, and over time the structure would probably be more stable too," says Dr. John Elter, PlugPower's vice president of research and system architecture.
Indeed, durability is the focus of the second goal. Today's membranes degrade with time and use, making fuel cells more costly to operate. "Nanotechnology is one path to improving stack life," Elter says. Specifically, a nano-structured electrode surface might prevent platinum particles from agglomerating and degrading the electrode's performance. "I hope we'll get an order of magnitude of improvement," Elter says. "But even if we double the stack life, that would also be very good."
The third goal involves reducing manufacturing costs by minimizing the amount of costly platinum required in an electrode. One approach involves using carbon nanotubes. "If you can get these tubes to stand on end on the membrane, you would have a much greater effective surface area, and the platinum loading would go down," Elter says.
Some nanotechnology researchers have reported staggering reductions in platinum loading-up to 98 percent reductions in some cases. Elter warns, however, that isolated lab results can be misleading, and more development will be required to achieve consistent, commercial-scale results. Still, he is optimistic about the prospects.
"There is a lot of promise in the literature, and tremendous momentum now," he says. "We should see a line of sight to an end game after a couple of years of research."
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