NTT-DEVELOPED SOLID-OXIDE FUEL CELL IS EFFICIENT, LONG-LASTING

TOKYO, Jul 22, 2008 (AsiaPulse via COMTEX) -- NTT | Quote | Chart | News | PowerRating -- The Energy and Environmental Systems Laboratories of Nippon Telegraph and Telephone Corp. (TSE:9432) has developed a solid-oxide fuel cell that is both highly energy-efficient and durable.

By improving the cell structure and the way unspent gas fuel is recovered and reused, NTT has developed a 1kw-class unit from a stack of 50 cells that generates power with an energy efficiency of 54 per cent and can operate for 1,000 hours. A smaller stack of 30 cells can operate with the same energy efficiency for 3,500 hours.

Solid-oxide fuel cells are the most energy-efficient type of fuel cells and can be configured as high-capacity power generators with promising applications in offices and factories. But typical solid-oxide fuel cells with an efficiency of around 55 per cent last for only several hundred hours. Through connecting cells serially to boost durability, the system can operate for tens of thousands of hours, but with an energy efficiency of just 20-30 per cent.

NTT used a lanthanum-nickel-iron oxide compound for the air electrode to improve overall performance. This material is both durable and a good conductor, and it allowed the company to fashion the cells in large diameters of 12cm. With conventional zirconia materials, the cells cannot be large, because the zirconia is brittle.

And to further boost efficiency, NTT inserted a tube inside the cell to recover fuel gas. If the amount of fuel used to generate power can be raised to about 80 per cent, it would lift the fuel cell's energy efficiency above 60 per cent.

NTT plans to continue working to improve the cell, aiming within two to five years to have a version that can operate stably for tens of thousands of hours.

(Nikkei)

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