Saturday, May 15, 2010

Bionic coating could help ships to economize on fuel

From : The Green Optimistic

Water ferns have tiny hairs that are super hydrophobic. Their properties, if applied in real life conditions to a sail boat, for example, could lead to a reduction of up to 10 percent of the boat’s fuel consumption by reducing friction.
Until now, the researchers didn’t quite understand how aquatic ferns work, but some scientists from the University of Bonn, Rostock and Karlsruhe showed the exact process in the journal Advanced Materials.
The scientists used the water fern salvinia molesta, which is extremely hydrophobic. Using such properties in swimsuits, for example, could make them quick-drying and ships would be very efficient. The salvinia molesta surrounds itself by a skirt of air, preventing the plant from coming into contact with the liquid. And the effect lasts a few weeks.

Hydrophobic materials had been discovered, but their properties don’t last that long – not to mention as long as to be put on ships who cruise for weeks/months. The best such material only has a few hours of stability, after which it vanishes. The challenge is to make hydrophobic materials that last at least as water ferns do.
The water fern has been found out to use its tiny hydrophobic whisk-like hairs on the surface of its leaves to repel water and keep it at distance. And that’s not all: “We were able to show that the outermost tips of these whisks are hydrophilic, i.e. they love water,” Professor Wilhelm Barthlott from the University of Bonn explains. “They plunge into the surrounding liquid and basically staple the water to the plant at regular intervals. The air layer situated beneath it can therefore not escape so easily.”
The professor also estimates that, by being huge fuel-guzzlers, ships could make a difference in the worldwide fuel savings if they’re “tuned” to be more efficient – “probably one percent of the fuel consumption worldwide could be saved this way,” he says.

Today, some antifouling coating method (but not bio) increases the ship's efficiency by reducing drag while also protecting the ocean from biocides that may leak.
Instead of biocides, used by much of the industry to keep barnacles off of the hull, a special silicone-based paint is used. The silicone paint covering the part of the hull below the waterline is credited for lowering the water drag enough to save 1200 tons of fuel per year for the 'Emma Mærsk' ship.

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