New life for a cell: the ceramic solution

NEW LIFE FOR A CELL: THE CERAMIC SOLUTION

Scientists have dreamed for years of creating an efficient, clean, quiet, electric-powered alternative to the dirty, noisy, internal combustion gas-powered vehicle. However, to date, electric vehicles haven't cut it: either they've been weighty, battery-packed behemoths able to go only small distances without a recharge -- or golf carts.

There has been an alternative to both internal combustion engines and batteries for a century and a half. Known as fuel cells, these devices combine the virtues of petroleum's hydrocarbon power and the battery's electrochemical power. But they've had a high weight-to-power ratio, which has made them unsuitable for use in vehicles.

Now researchers at Argonne National Laboratory appear to have found a way around this shortcoming, by using advanced ceramics to construct lightweight, efficient fuel cells. If their initial successes with lab models are borne out in scaled-up trials, the result could be all-electric cars, helicopters, even airplanes.

Heretofore, cells were made of heavier materials, and most designs were expensive because they didn't operate directly on conventional fuels like gasoline. Instead, they required components that would break down the fuel into simpler gases like hydrogen or carbon monoxide. In the Argonne design, four types of ceramics are fabricated into a design resembling corrugated cardboard, with alternating channels for fuel and air. The interior wall of the air channel is a ceramic layer of lanthanum manganite doped with strontium to act as the cathode in electric generation. The fuel channel is lined with a layer of yttria-stabilized zirconia and cobalt or nickel to serve as the anode. Yttria-stabilized zirconia is used as the electrolyte -- the middle of the three-part sandwich. When a number of fuel cells are connected, a fourth layer, made of lanthanum chromite doped with magnesium, is used to connect them into electrical series.

The permeable ceramic walls of the electrodes are integral to the chemical reaction by which the fuel is oxidized to create a flow of electrons. The unit also operates at a high enough temperature, about 1,000 degrees C., that the fuel is turned into the required gases directly in the cell without the need for additional hardware.

''This fuel cell is all solid state and composed only of active ingredients, so it can be fabricated in very thin layers that are very lightweight and low volume,'' says chemist Darrell Fee, who leads the Argonne team developing the cell.

According to Fee, the design could be used to build a 100-kilowatt cell -- the equivalent of a 132-horsepower internal combustion engine weighing 600 pounds -- that's a cube eleven inches on a side. Its total weight, including the components needed to cool it and make it the functional equivalent of a conventional engine, would be about 300 pounds.

An internal combustion engine delivers only about 30 per cent ofthe potential heating power of the fuel it burns. By converting fuel into power by direct chemical means instead of burning it, the fuel cells attain an efficiency of nearly 50 per cent. And when you're sitting at a red light, you can shut the cell off so you won't burn any fuel. As long as the temperature in the cell stays within operating range, the instant you feed it gas again it'll fire right up -- charge right up, actually -- and away you'll quietly whir, spewing out nothing more polluting than carbon dioxide and water.

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