Findings Could Improve Fuel Cell Efficiency

Mar 19, 2008

Researchers at Duke’s Pratt School of Engineering have developed a membrane that allows fuel cells to operate at low humidity and theoretically at higher temperatures.

A new type of membrane based on tiny iron particles appears to address one of the major limitations exhibited by current power-generating fuel cell technology.

While there are many types of fuel cells, in general they generate electricity as the result of chemical reactions between an external fuel -- most commonly hydrogen -- and an agent that reacts with it. The membrane that separates the two parts of the cell and facilitates the reaction is a key factor in determining the efficiency of the cell.

Fuel cells are commonly used in such settings as satellites, submarines or remote weather stations because they have no moving parts, do not require combustion and can run unattended for long periods of time. However, current fuel cells lose efficiency as the temperature rises and the humidity falls.

Researchers at Duke University’s Pratt School of Engineering have developed a membrane that allows fuel cells to operate at low humidity and theoretically to operate at higher temperatures. They reported their findings online in the Journal of Membrane Science.

“The current gold standard membrane is a polymer that needs to be in a humid environment in order to function efficiently,” said Mark Wiesner, Ph.D., a Duke civil engineering professor and senior author of the paper. “If the polymer membrane dries out, its efficiency drops. We developed a ceramic membrane made of iron nanoparticles that works at much lower humidities. And because it is a ceramic, it should also tolerate higher temperatures.

“If the next series of tests proves that fuel cells with these new membranes perform well at high temperatures, we believe it might attract the type of investment needed to bring this technology to the market,” Wiesner added.

The membrane most commonly used today, known as Nafion, was discovered in the 1960s. As the temperature rises, the polymer becomes unstable and the membranes dehydrate, leading to a loss of performance.

In addition to its temperature and heat limitations, Nafion is also much more expensive to produce than the new membrane, Wiesner said, adding that membranes make up as much as 40 percent of the overall cost of fuel cells.

Wiesner said he believes that future experiments will demonstrate the new membrane’s ability to operate at higher temperatures.

“The efficiency of current membranes drops significantly at temperatures over 190 degrees Fahrenheit,” he explained. “However, the chemical reactions that create the electricity are more efficient at high temperatures, so it would be a big improvement for fuel cell technology to make this advance.”

An interesting outcome of these experiments is leading Wiesner down a new and related research path. As a result of the chemical reactions that create the electricity, small amounts of water are created as a byproduct.

“In the current technology, this water is used by the system to maintain the humidity within the cell,” Wiesner said. “The water produced in these reactions is of high purity. So, if a fuel cell membrane could be developed that wasn’t reliant on humidity, this water could be used for other purposes.”

In addition to these experiments, Wiesner’s team plans to study new ways of fabricating the membranes to improve their durability and flexibility.

The study is available here.

Source: Duke University

Explore further: Researchers develop scalable methods for manufacturing metamaterials

add to favorites email to friend print save as pdf

Related Stories

New study outlines 'water world' theory of life's origins

9 hours ago

(Phys.org) —Life took root more than four billion years ago on our nascent Earth, a wetter and harsher place than now, bathed in sizzling ultraviolet rays. What started out as simple cells ultimately transformed ...

Carbon nanotubes find real world applications

Mar 31, 2014

No one disputes that carbon nanotubes have the potential to be a wonder technology: their properties include a thermal conductivity higher than diamond, greater mechanical strength than steel – orders of ...

Recommended for you

Novel technique opens door to better solar cells

Apr 14, 2014

A team of scientists, led by Assistant Professor Andrivo Rusydi from the Department of Physics at the National University of Singapore's (NUS) Faculty of Science, has successfully developed a technique to ...

User comments : 0

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...