Published on October 12th, 2009 | by Tina Casey
“Mystery” Ceramic Could Lead to Cheaper, Stronger Hydrogen Fuel Cells
They don’t know how it works, but it does.
A team of researchers at Georgia Tech has developed a new high-tech ceramic material that could make solid oxide fuel cells less costly and less finicky, and much more durable and efficient. The material is called Barium-Zirconium-Cerium-Yttrium-Ytterbuim Oxide. [Ed note: Say that three times fast and you get a gold star.] I don’t know if it’s any less of a tongue twister, but it’s known as BZCYYb for short.
Solid oxide fuel cells are of interest because they can generate energy without the need for an expensive catalyst such as platinum, which is typically used in hydrogen fuel cells. While nanotechnology is enabling the development of hydrogen fuel cells that use less platinum, with BZCYYb the prospects look good for ditching the precious metal entirely in favor of more sustainable technology—if solid oxide systems can be developed in a commercially viable form, that is.
Solid Oxide Fuel Cells and the Problem of Heat
Heat is one problem standing between solid oxide technology and the mass market. In conventional solid oxide fuel cells, the anode (the part that conducts incoming electric current) is a composite that includes a ceramic called yttria-stabilized zirconia (YSZ). YSZ excels as a catalyst and a conductor, but researchers at Georgia Tech note that it loses conductivity at low temperatures, requiring an operating temperature as high as 1,000 degrees Centigrade. Sulfur contamination and carbon deposits are two other significant problems with YSZ anodes. To counter these three factors, solid oxide fuel cells that use YSZ have high complexity systems that employ low sulfur fuel and exotic heat-tolerant materials, leading to higher costs, less durability, and lower efficiency.
The BZCYYb Difference
BZCYYb resolves the heat problem through its ability to retain conductivity at temperatures as low as 500 degrees centigrade. It also resists carbon deposits and it tolerates relatively high concentrations of sulfur compared to YSZ. That’s where the mystery lies. Researchers have not yet pinpointed the factors behind BZCYYb’s clean-running capabilities, but they believe that the material’s more powerful catalytic performance could be enabling it act on sulfur and hydrocarbons more effectively. With these three problems resolved, BZCYYb could lead to the design of more simple, compact, and cost-effective solid oxide systems. Potentially BZCYYb could be used to coat conventional YSZ anodes, or replace them entirely.
The Fuel Cell of the Future
Solid oxide technology is one among several avenues that researchers are exploring to make fuel cells less expensive and more light, compact, simple, and flexible. For example, the company Full Cycle Energy has licensed a non-platinum fuel cell based on a high performance alkaline membrane that enables it to use biofuels in addition to hydrogen. The Department of Energy is pitching in with millions in research funds, and the U.S. military is eager to adopt more robust, portable power sources, so look for a continuing wave of new developments in the near future.
Image: BotheredByBees on flickr.com.