Fuel cells have been touted as the environmentally sound replacement for everything from AAA batteries to the massive steam turbines that run our power plants. The type of fuel cell that has received the most attention in recent years is one that uses hydrogen as a fuel.

Hydrogen fuel cells are exceptionally clean, producing nothing but water and heat as byproducts, but there’s a rub. The majority of commercially available hydrogen is produced from hydrocarbons by an energyconsuming process, which also produces carbon dioxide, a greenhouse gas. Storing and distributing this highly flammable gas is also problematic. As chemical engineer Steven McIntosh observes, “The hydrogen economy will be a long time coming.”

The Solid Oxide Alternative

McIntosh himself focuses on solid oxide fuel cells that can use any combustible fuel, including gasoline, diesel and biofuels. “Because they take advantage of existing infrastructure, solid oxide fuel cells will give us the ability to realize the potential of fuel cells in the near future,” he says.

McIntosh is working to find high-performance anode materials that provide the ideal balance of catalysis and conductivity. The requirements for these materials are especially stringent, as solid oxide fuel cells require temperatures of over 700 degrees Celsius to operate; in addition, the ideal anode would also suppress the formation of carbon, which is a byproduct of transforming hydrocarbons into electricity.

An Anode Library

McIntosh’s approach is to develop a library of possible mixed oxide materials that may prove useful as an anode and subject each of them to a series of tests that help him better understand their properties.

“We know that if you pull oxygen out of these materials, you improve the conductivity,” he says, “but we are still trying to understand the limiting factors.”

One of McIntosh’s graduate students, Michael van den Bossche (’09), is characterizing the effectiveness of a lanthanum-chromium-strontium-manganeseoxide anode for solid oxide fuel cells powered by methane. He is varying the proportion of elements, conducting the reaction at different temperatures and varying the oxygen content to determine the effects of these changes on the ratio of carbon monoxide to carbon dioxide produced.

In McIntosh’s view, solid oxide fuel cells would be ideal for home use and distributed power generation. “Because they could be used to generate heat as well as electricity, they are more efficient than traditional energy sources — and they would be considerably more versatile since they are not limited to a single kind of fuel,” he says.

Originally published in the fall 2006 issue of Explorations. Published with permission.