Solid-oxide fuel cells offer the highest efficiency, but need to use expensively purified fuel and operate at high temperatures. Now both those problems could be overcome by new technology from Georgia Tech. Look for solid-oxide fuel cells in mainstream applications within 10 years. R.C.J.
Solid-oxide fuel cells offer high efficiency--80 percent compared to 50 percent for hydrogen fuel cells--and can utilize a wider variety of fuels, including hydrogen, natural gas or propane. But they also are easily contaminated by sulfur and carbon build-up on anodes that reduce these advantages. A new kind of electrode material could overcome contamination problems using an auto-cleaning process that could also lower their cost. Traditional anode electrodes can be fouled by as little as 1 part per million of sulfur in the fuel, requiring the costly step of purifying fuel before it is used. The ceramic electrode material can tolerate sulfur contaminants in concentrations as high as 50 ppm. The ceramic material, which was discovered after extensive experimentation, is composed of five different elements: barium, zirconium, cerium, yttrium and ytterbium. Despite the complex formulation, it can be cast into relatively inexpensive anode electrodes, the researchers said.