Text: Eric Tipan / Photos: CSIRO | posted April 29, 2016 14:19
Membrane mimicking cactus skin developed by Aussie scientists
The lowly cactus may seem unassuming to the ordinary person but scientists in Australia have discovered something in its skin that may soon change the way fuel cell vehicles (FCVs) manage heat, water and its limited power resource.
Scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO) have looked deeply into the inner workings of cactus skin and are studying its amazing ability to manage water in harsh, desert environments.
"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," said CSIRO researcher Cara Doherty.
This is what inspired CSIRO scientists to develop a membrane that mimics the cactus skin in order to improve the ‘efficiency of the fuel cells by a factor of four.’
When exposed to high temperatures, the membrane’s water repellant skin keeps the fuel cells hydrated, which frees up power for other uses such as increasing range or speed instead of using it on the ‘power-hungry radiator’ to keep the fuel cells hydrated.
"Fuel cells, like the ones used in electric vehicles, generate energy by mixing together simple gases, like hydrogen and oxygen. 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," said Aaron Thornton from CSIRO.
The membrane eliminates the need to dedicate power simply for fuel cell hydration and allow for better water and heat management in order to increase the performance of FCVs.
“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, and this means that fuel cells can remain hydrated without the need for bulky external humidifier equipment. We found that the skin made the fuel cells up to four times as efficient in hot and dry conditions," added Doherty.
As automakers struggle to find ways to raise the performance and range of FCVs, this development is definitely a step forward in the right direction.
"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. This research addresses this hurdle, bringing us a step closer to fuel cell electric vehicles being more widely available,” said Professor Young Moo Lee from Hanyang University (collaborated with CSIRO on the project).