Omnivorous fuel cells

A prototype fuel cell runs on a wide range of fuels without turning up the heat.

Fuel cells are the most efficient way to convert chemical energy into electricity. But most either operate at high temperatures or require very pure hydrogen fuel. Superprotonic, a startup company in Pasadena, CA, is developing a fuel cell that can handle dirty hydrogen at relatively low temperatures. It could thus use hydrogen produced from other fuels--such as natural gas or ethanol--by a simple device called a "reformer."

In a fuel cell, an electrolyte is sandwiched between an anode and a cathode. A catalyst at the anode splits hydrogen into electrons and protons. The protons can pass through the electrolyte, but the electrons can't. So in order to reach the cathode, the electrons travel through an external electrical circuit, where they can be used to recharge a battery or power a device. At the cathode, another catalyst helps the protons and electrons combine with oxygen sucked from the air to form water--the fuel cell's only waste product.

Superprotonic's fuel cells rely on a material called a solid acid, first tested as an electrolyte in 2001 by Caltech materials-science and chemical-engineering professor Sossina Haile. "What makes our fuel cell special is the nature of this electrolyte," she says. Solid-acid fuel cells operate at what Haile calls a Goldilocks temperature: not too hot, not too cold.

Omnivorous Fuel Cells
Tue, 06 Jan 2009 05:00:00 GMT

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