Engineers at The University of Texas at Austin have identified a material that would allow hospitals or other independent facilities to generate electricity from stationary fuel cells that run on natural gas.
Unlike fuel cells developed for hydrogen-fueled autos, Professor John B. Goodenough and postdoctoral fellows in his laboratory have identified a ceramic material for stationary power needs that efficiently converts natural gas directly into electricity.
"The direct use of natural gas saves a processing step," said Goodenough, who holds the Virginia H. Cockrell Centennial Chair in Engineering.
The researchers' double-perovskite ceramic conducts both electrons and oxide ions, and promotes the chemical reactions of the fuel cell. In addition, the new material is tolerant to sulfur impurities in natural gas. Their findings will be published in tomorrow's issue of the journal Science.
In the 1980s and 1990s, Goodenough identified the electrode materials underlying all the rechargeable lithium batteries of today's wireless devices. This newest work moves his successful development of energy materials from compact power storage to the massive power-production market. In this new arena, Goodenough has discovered his double-perovskite ceramic anode is about twice as effective as the alternative that operates on natural gas.
"Instead of getting electricity only off the power grid, solid-oxide fuel cells would allow you to get some of it from natural gas, which would move us towards a distributed power system, less vulnerable to terrorist attacks or power outages," Goodenough said. He added that countries without a power grid, or hospitals and other critical institutions are among those who would benefit from this alternate electricity source.
Converting natural gas into electricity using solid-oxide fuel cells requires high temperatures, so they work best for stationary purposes rather than serving as power sources for cars. Because of the high-temperature operation, waste heat from a power plant could improve solid-oxide fuel cells' overall efficiency of electric power generation.
The new electrode material can work with natural gas at what is considered a reasonable temperature (800 degrees Celsius/1,472 degrees Fahrenheit) for catalyzing chemical reactions to produce electricity.
The conventional solid-oxide fuel cell anode, which is the electrode where fuel is oxidized, is a porous nickel and electrolyte composite that can only be used with pure hydrogen. Goodenough estimates his double-perovskite ceramic anode is about twice as effective as the only other known sulfur-tolerant anode material that can operate with natural gas.
The general advantages of the double perovskite as an anode occurred to Goodenough last summer, when his former student, Dr. Ronald Dass, showed him that a double-perovskite material that contained manganese and molybdenum was oxygen-deficient and stable in a hydrogen atmosphere. Goodenough assigned his postdoctoral fellow, Zheng-Liang Xing, to test his idea. On Xing's departure in the autumn, Yun Hui Huang joined Goodenough's group and completed the testing, with magnesium substituting for the manganese in the anode material.
"We went right to the lab, and saw that the idea worked," Goodenough said.
For photos of Dr. Goodenough and research group members, go to: http://www.engr.utexas.edu/news/action_shots/pages/GoodenoughApril13.cfm
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About UT's Cockrell School of Engineering:
The University of Texas at Austin's Cockrell School of Engineering ranks among the top six public engineering schools in the United States. With the nation's fourth highest number of faculty elected members of the National Academy of Engineering, the School's more than 7,000 students gain exposure to the nation's finest engineering practitioners. Appropriately, the School's logo, an embellished checkmark used by the first UT engineering dean to denote high quality student work, is the nation's oldest quality symbol. The School maintains a Web site at http://www.engr.utexas.edu