Supersurface Could Shrink Power Plants

November 04, 2009

Sounds trippy, but it's true: mushrooms and lotus leaves are the inspiration for a superhydrophobic surface created by Duke University scientists that has the potential to make power plants super-efficient.

"In power plants, the majority of the space is taken up by bulky condensers," says Chuan-Hua Chen, assistant professor of mechanical engineering and materials science at Duke. Conventional condensers, which are needed to reject heat in power plants' cooling systems, rely on slick coatings and gravity. Chen and his team turned to nature for better ideas.

Water rolls right off a lotus leaf because its rough surface traps air under the droplets. When a mushroom reproduces, the discharge of spores is actually powered by the energy released when dew droplets merge on them. To replicate these effects, the scientists etched pillars a few microns tall into silicon and added carbon nanotubes that mimic the rough lotus leaf. When cooled, the synthetic surface causes water droplets to form quickly and jump--like a balloon bouncing off your hand.

Chen says this makes a condenser so efficient that its size could be reduced as much as 10 times what it is now. Plus, the surface doesn't need gravity to work so it could even be used in outer space. A Duke University video shows it in action:

Grad student Jonathan Boreyko is leading work on building miniaturized condensers with the superhydrophobic surface. Chen says that while there are ways to make such surfaces inexpensively, the focus now is on durability. With supersurfaces, we could get more out of the power plants we've already got, making each drop truly count.

Photo: Chuan-Hua Chen (right) and Jonathan Boreyko (left), demonstrate the superhydrophobic surface, located under the pipette. Credit: Duke University Photography.