Research May Lead To Improved Fuel Cell Design

Dr. Steven Bergens and Dr. Rod Wasylishen from the Department of Chemistry led the team, which produced images revealing how water behaves inside hydrogen fuel cells. Their preliminary findings appear in the Journal of the American Chemistry Society. The fuel cells are touted as an alternate-energy option to power everything from computers to houses and cars.

Although tremendous strides have been made in hydrogen fuel cell technology, including pilot programs using hydrogen-powered buses and automobiles, the technology relies on a certain amount of trial and error.

“This is the first time anybody has simultaneously observed the water in all parts of an operating fuel cell,” Bergens said of the experiment. “It’s interesting because you can have all the high-tech science you can dream of in a fuel cell, but form just one drop of water in the wrong place, and it’s a bad day. This is an incredibly simple, but complicated problem.”

Hydrogen fuel cells generate electricity through simple chemical reactions. Hydrogen molecules pumped into one side of a fuel cell react with platinum, breaking into constituent protons and electrons. The electrons leave the fuel cell via wire to power a computer or propel a car, before returning to the oxygen side of the fuel cell. The protons, on the other hand, pass through a membrane in the fuel cell and combine with the electrons and oxygen pumped into the other side of the cell, forming water.

A major problem in hydrogen fuel cell development lies in the creation of that water, the energy source's only byproduct. Problems arise when too much water is created, blocking tiny channels the hydrogen and oxygen travel along inside the fuel cells. Increasing the flow of oxygen is one possible solution, but there's a wrinkle -- greater flow of oxygen (air) would cool the cell and dehydrate the membrane, which must remain moist in order for protons to pass through it.

"It's a crucial problem," said Bergens. "You can't let the membrane get too dry or the protons can't pass through it, and you can't let a drop of water form or it will stop oxygen and hydrogen from passing through the channels and block the catalysts. You need to strike a delicate balance."

To better understand that balance, the research team had a bright idea. "MRI observes protons in water, so why not run a fuel cell in an MRI magnet and then watch the water?" Bergens recalled.

It turns out there were be plenty of reasons to be cautious, particularly the fact that the project would involve a fuel cell generating electricity in the strong magnetic field of the MRI spectrometer.

In using MRI to examine fuel cells, "everything that can go wrong does go wrong," according to Kirk Feindel, a graduate student of Wasylishen's who worked on the project with Bergens, graduate student Logan LaRocque, and Dieter Starke, a machinist in the department.

"Ideally you'd want a system with a homogenous magnetic field," Feindel said, explaining that a device with gold, platinum and an electrical current hardly meets those ideal conditions.

But the team managed to capture striking images of water within the fuel cell, illustrating how water builds up then recedes, along with the fuel cell's efficiency. By understanding what goes on in the cell while it operates, "we can come up with better designs to avoid blockages," Bergens said.

"We've been getting e-mails from labs around the world that want to work on this," he added. The team has also been contacted by Ballard Power Systems. The Vancouver-based firm is regarded as a leader in fuel cell technology.

The idea now is to design an even smaller fuel cell which will, in turn, provide a clearer picture of what goes on inside working fuel cells.

Related links:

The U of A Department of Chemistry website:http://www.chem.ualberta.ca/

Journal of the American Chemistry Society online:http://www.cbcrp.org/research/PagePeriodical.asp?periodical_id=298

The Ballard Power Systems website:http://www.ballard.com/