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Redesigned fuel cell sets world recordfor output

Issue 7 and Volume 100.

Redesigned fuel cell sets world recordfor output

The U.S. Department of Energy (DOE) recently reported that a new configuration for the all-solid-state ceramic fuel cell has boosted its electric power output by more than a third, in addition to improving its strength and durability.

Westinghouse Electric Corp.`s Science & Technology Center in Pittsburgh developed the technology in co-sponsorship with the DOE. The new design, known as the “tubular” solid-oxide configuration, is the most advanced in a family of fuel cell concepts now being readied for the 21st-century energy market.

Like all fuel cells, solid-oxide technology produces power by an electrochemical reaction, rather than by combustion. Unlike other fuel cells, however, the solid-oxide fuel cell uses all solid materials. While other concepts use a liquid electrolyte, the solid-oxide technology employs ceramics for its electrodes, electrolytes and interconnections.

Originally, the tubular solid-oxide concept consisted of layers of electrode and electrolyte materials fabricated over a porous zirconia support tube. For much of the last 15 years, DOE and Westinghouse engineers considered the support tube essential for structural support.

Now, Westinghouse engineers have found a way to eliminate the support tube, removing a costly step in cell manufacturing and improving the cell`s performance. The new design uses the cathode layer–the air electrode–as the tubular cell`s basic mechanical support structure.

For all three fuels tested–natural gas, diesel and jet fuel–the new configuration boosted power output by 35 percent. Producing 27 kW, the tests set a world record output from a single solid-oxide fuel-cell module.

Increased power output means future commercial fuel-cell generators can be smaller, reducing materials and manufacturing costs. More efficient operation will also lower operating costs.

Each of the two solid-oxide fuel-cell generators in the test program operated virtually flawlessly for more than 5,500 hours. During the tests, operators cycled the fuel cells from their typical 1,800 F operating temperature down to room temperature and back up five times with no measurable harm.

In the past, thermal cycling has ultimately degraded voltage. In separate lab tests, engineers similarly cycled two individual solid-oxide cells more than 100 times with no effect on performance.

The test results exceeded all expectations of both Westinghouse and the DOE.