Scientists studying ways to produceclean energy have long known thebenefits of fuel cells, devices thatconvert hydrogen and oxygen into electricityand heat. One such device, the protonexchange membrane fuel cell (PEM), usespure hydrogen gas to produce clean, highlyefficient, renewable power — mostcommonly for applications such as cars,lighting, communications, and navigation.But because hydrogen is expensive toproduce ($5 to $8 per kilogram of hydrogen)and is difficult to store and deliver, apractical application for a PEM fuel cell hasdelayed its commercial debut.

To help solve this problem, researcher Gerardine Botte is developing a device that produces hydrogen for PEM fuel cells at a low cost using the common household chemical ammonia.

Called an ammonia in situ hydrogen generator, the device uses energy fromsolar panels to pass ammonia, whichcontains nitrogen and hydrogen, through acell that separates these two compounds.The nitrogen is harmless and is releasedinto the air. The pure hydrogen is used topower a PEM fuel cell.

Through theoretical computer modeling, this method has been shown to produce hydrogen at a cost of $1.70 per kilogram of hydrogen, which includes the cost of ammonia and solar energy.

“That is a 75 percent savings over other hydrogen-generating methods,” says Botte, an assistant professor of chemical engineering at Ohio University.

Botte also has shown that the generator requires very little energy to operate, which lowers operating temperatures and makes it practical for commercial use. In theory, Botte has shown that the generator consumes only 1.55 kilowatt-hours per kilogram of hydrogen. Since a PEM fuel cell produces 33 kilowatt-hours per kilogram of hydrogen, the generator could operate by using a small portion of the energy produced by the fuel cell. That’s a net of31 kilowatt-hours or enough to power ahome daily. The fuel cell and generatorwork together to provide this energy, eliminatingproblems with hydrogen storageand delivery, Botte says.

“That is the beauty of it — you don’t need to store hydrogen to run the PEM at night, which makes the generator a flexible device to operate,” says Botte, whose research is funded by a grant from Ohio University’s 1804 Fund.

Botte, who has recently submitted a U.S. patent on the generator, now is focused on testing better, less costly electrode materials that are used to separate the nitrogen from the hydrogen in ammonia.

The researcher also is working with Ohio University engineer David Bayless on a related fuel cell project that uses coal as a fuel source. Bayless, director of the Ohio Coal Research Center, is focusing on using Ohio coal, an abundant fuel source in Appalachia, with a planar Solid Oxide Fuel Cell (SOFC) to produce electricity and heat. Through a $4 million grant from the U.S. Department of Energy, Bayless is integratingthese fuel cells with gasified coalcalled syngas. The process produces hydrogen,electricity, and an intense amount ofheat, which the fuel cell can withstandbecause it’s made of ceramic material, saysBayless, an associate professor of mechanicalengineering. “The waste heat from thefuel cell can be used to make steam forproducing electricity — enough to generateheat for an entire building,” he says.

But syngas also contains harmful pollutants such as mercury and sulphur. The team now is examining which path would be most economical: develop a new fuel cell that can remove the pollutants and leave almost pure hydrogen, or figure out ways to clean the syngas before it passes through the planar SOFC.

“It will come down to economics,” Bayless says. “It’s just a question as to which path is the cheapest.”

For more information about fuel cell research atOhio University, visit www.ohio.edu/ohiocoal.