Cactus Skin Could Improve Fuel Cell Performance

Researchers from the Commonwealth Scientific and Industrial Research Organisation in Australia and Hanyang University in Korea have published a report in Nature this week that promises greater efficiency for fuel cells. Yes, we know that fuel cell cars won’t be a practical alternative to electric cars until someone figures out how to extract hydrogen from water or hydrocarbons without using less energy than the liberated hydrogen has to offer, but that is a subject for someone else to research.

Fuel cell membrane from cactus skin

A fuel cell works by passing electrons through a porous membrane. Actually, porous might be a bit of an overstatement. The openings are microscopic in size. “Fuel cells, like the ones used in electric vehicles, generate energy by mixing together simple gases, like hydrogen and oxygen,” says Dr Aaron Thornton, a researcher at CSIRO and a co-author of the study report.

“However, in order to maintain performance, proton exchange membrane fuel cells — or PEMFCs — need to stay constantly hydrated. At the moment this is achieved by placing the cells alongside a radiator, water reservoir and a humidifier. The downside is that when used in a vehicle, these occupy a large amount of space and consume significant power.”

The researchers decided to study the skin of cactus plants, which thrive by retaining water in harsh and arid environments. As a result of their study, they created a membrane that mimics the characteristics of cactus skin. According to CSIRO researcher and co-author Dr Cara Doherty, “A cactus plant has tiny cracks, called stomatal pores, which open at night when it is cool and humid, and close during the day when the conditions are hot and arid. This helps it retain water.

“This membrane works in a similar way. Water is generated by an electrochemical reaction, which is then regulated through nano-cracks within the skin. The cracks widen when exposed to humidifying conditions, and close up when it is drier. This means that fuel cells can remain hydrated without the need for bulky external humidifier equipment. We also found that the skin made the fuel cells up to four times as efficient in hot and dry conditions.”

Professor Young Moo Lee from Hanyang University, who led the research, said that this could have major implications for many industries, including the development of electric vehicles. “At the moment, one of the main barriers to the uptake of fuel cell electric vehicles is water management and heat management in fuel cell systems,” Professor Lee said. “This research addresses this hurdle, bringing us a step closer to fuel cell electric vehicles being more widely available. This technique could also be applied to other existing technologies that require hydrated membranes, including devices for water treatment and gas separation.”

In case you think such breakthroughs come easily, bear this thought in mind. The CSIRO/Hanyang University team has been working together for more than 10 years. Maybe in another 10 years, a different team of researchers will figure out how to obtain free hydrogen at reasonable cost. Don’t write off the hydrogen fuel cell just yet.

Spurce: Electric Cars Report    Image credit: CSIRO

Steve Hanley

Closely following the transition from internal combustion to electricity. Whether it's cars, trucks, ships, or airplanes, sustainability is the key. Please follow me on Google + and Twitter.