some examples for your review.
National Hydride Testing Established
The Department of Energy (DOE) has selected a team headed by Southwest Research Institute (SwRI, P.O. Drawer 28510, San Antonio, TX 78228-0510) to develop and operate a national facility to test materials for their ability to store hydrogen.
Because of the burgeoning interest in hydrogen as a fuel source for fuel cells, the DOE established the national testing facility at SwRI to assess the performance of new hydrogen-storing materials and systems and to focus national research efforts on those that show the most promise.
The Institute team was awarded a four-year, $3 million grant from the Office of Renewable Energy to develop and operate a standard testing and certification program to assess the performance, safety and life cycle of promising metal hydride, chemical hydride, and carbon-based hydrogen storage systems. Working with industry and the government, the Institute will develop an accepted set of performance and safety evaluation standards and then evaluate new materials according to those standards.
"This program is driven by the realization that hydrogen storage is critical to making fuel cells a reality," says Michael A. Miller, manager of the materials characterization and development section in SwRI's mechanical and materials engineering division. "Conventional methods of storing compressed hydrogen in cylinders for use with fuel cells raise several safety concerns, particularly in automotive applications."
To improve fuel cell technology, industry is developing alternative methods for hydrogen storage. Emerging methods include metal hydride, chemical hydride, and carbon-based storage technologies that adsorb and store hydrogen at low pressures. Several organizations have developed promising new low-pressure storage materials or techniques that can store more hydrogen than previously believed and release it at a controlled rate.
The team consists of SwRI, Teledyne Energy Systems, Energy Conversion Devices, Inc. and the National Hydrogen Association (NHA). As part of this program, the Institute will design laboratory equipment and instrumentation and will manage and operate the new hydrogen storage national testing facility to be located at SwRI's San Antonio location. For more information, contact James Pryor, communications department; Tel: 210/522-2258; Fax: 210/522-3547.
Teledyne Energy Systems will provide hydrogen-generation equipment for use in refueling studies, and Energy Conversion Devices will provide materials and prototype hydrogen storage systems for benchmarking test procedures and establishing performance specifications. NHA will work closely with the Institute to draft testing standards and safety procedures.
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RARE EARTHS
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Delphi Develops 3-Way Material
Delphi Technologies, Inc. (5725Delphi Dr., Troy, MI 48098; Tel: 248/813-2000) has developed rare earth catalysts capable of performing multiple duties. Oxygen ion conducting/oxygen storage (OIC/OS) materials can be employed in numerous applications, including solid oxide fuel cells (SOFC) for energy conversion, electrochemical oxygen sensors, oxygen ion pumps and structural ceramics. They can also be used in hydrogen sensors, in catalysts for methanol decomposition, as potential hosts for immobilizing nuclear waste, as oxygen storage materials in three-way-conversion (TWC) catalysts, as well as in other applications where oxygen storage capacity and/or oxygen ion conductivity are factors.
Fully or partially stabilized zirconia, as well as other common solid electrolytes, have a number of drawbacks. To achieve sufficiently high conductivity and to minimize electrode polarization, the operating temperatures have to be in excess of 800°C to1,000°C. For solid oxide fuel cells, reducing the operating temperatures to less than 800°C would result in advantages such as greater flexibility in electrode selection, reduced maintenance costs, reduction in the heat insulating parts needed to maintain the higher temperatures and reductions in carbonaceous deposits (soot) that foul the operation of the fuel cell.
John Gerard and Bortun I.Anatoly, in U.S. Patent 6,387,338, found that when used as oxygen storage materials in three-way-conversion catalysts, the OIC/OS material could be supported on a substrate as part of the three-way-conversion catalyst. When exposed to an exhaust environment, the combined material would exhibit substantially equal or increased three-way-conversion capabilities compared to a conventional catalyst.
Electrolytes From Nano Materials
Ion conducting solid electrolytes constructed from rare earth nanoscale precursor material have been developed by Nano Products Corp. (CEO Tapesh Yadav, 4330 Longs Peak Ct., Longmont, CO 80504; Tel: 970/535-0629, ext. 244, Fax: 970/535-9309).
Nanocrystalline powders are pressed into disc structures and sintered to the appropriate degree of densification. Metallic material is mixed with 0 vol% to 65 vol% nanostructured electrolyte powders to form a cermet mix. This mix is then coated on each side of the disc and fitted with electrical leads.
The electrical conductivity of the resulting Ag/YSZ/Ag cell exhibited about an order of magnitude enhancement in oxygen ion conductivity. As an oxygen-sensing element in a standard O2/Ag/YSZ/Ag/N2 set up, the nanocrystalline YSZ element exhibited commercially significant oxygen ion conductivity at low temperatures. The material can be used to prepare nanostructured ion conducting solid electrolytes for a wide range of applications, including sensors, oxygen pumps, fuel cells, batteries, electrosynthesis reactors and catalytic membranes.
In U.S. Patent 6,387,560, Tapesh Yadav and Hongxing Hu describe how to enhance the ion-conductivity of solid electrolytes by preparing nanostructured solid electrolytes. Nano Products reduced the electrolyte thickness with the use of nanostructured precursors of solid electrolytes. The size of the solid electrolyte and electrode grains are less than 100 nm. Nano Products developed manufacturing techniques to reduce the cost and operate products that incorporate oxygen-ion conductors. The process can be readily incorporated with conventional methods for manufacturing products containing ion-conducting electrolytes. |
