Mar 172010
 

Hydrogen from waste

Now scientists have found a way to use ambient noise to turn water into usable hydrogen fuel

We recently looked at a breakthrough in using sunlight to create hydrogen but now scientists have found a way to use ambient noise to turn water into usable hydrogen fuel. The process harvests small amounts of otherwise-wasted energy such as noise or stray vibrations from the environment to break the chemical bonds in water and produce oxygen and hydrogen gas.

Materials scientists at the University of Wisconsin-Madison grew nanocrystals of two common crystals, zinc oxide and barium titanate, and placed them in water. When pulsed with ultrasonic vibrations, the nanofibers flexed and catalyzed a chemical reaction to split the water molecules into hydrogen and oxygen.

When the fibers bend, asymmetries in their crystal structures generate positive and negative charges and create an electrical potential. This phenomenon, called the piezoelectric effect, has been well known in certain crystals for more than a century and is the driving force behind quartz clocks and other applications.

The researchers applied the same idea to the nanocrystal fibers. “The bulk materials are brittle, but at the nanoscale they are flexible,” says UW-Madison geologist and crystal specialist Huifang Xu. He likened them to the difference between fiberglass and a pane of glass.

Smaller fibers bend more easily than larger crystals and therefore also produce electric charges easily. So far, the researchers have achieved an 18 percent efficiency with the nanocrystals, higher than most experimental energy sources.

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