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Use of energy waste to transform water into hydrogen fuel
Scientists at the University of Wisconsin-Madison have devised a way to collect small amounts of residual energy and harness it to turn water into a usable hydrogen fuel.
The process is simple, efficient, and recycles otherwise wasted energy.
"This study offers a simple and cost-effective technology for direct water separation that can generate hydrogen fuels by harnessing energy waste such as noise or vibrations from the environment," the authors write in a new paper, published March 2 in the Journal of Physical Chemistry Letters.
The researchers, led by UW-Madison geologist and crystal specialist Huifang Xu, developed nanocrystals from two common crystals, zinc oxide and barium titanate, and placed them in water. By applying ultrasonic vibrations to them, the nanofibers flexed and catalyzed a chemical reaction that split the water molecules into hydrogen and oxygen.
When the fibers are bent, the asymmetries of their crystalline 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 watches and other applications.
Xu and his colleagues applied the same idea to the fibers of the nanocrystals. "Larger materials are fragile, but at the nanoscale they are flexible," says Xu; just like the difference between fiberglass and a glass panel.
Smaller fibers bend more easily than larger crystals and therefore also easily produce electrical charges. So far, researchers have achieved an impressive 18% efficiency with nanocrystals, higher than most experimental energy sources.
With this type of technology, we can take advantage of energy waste and convert it into useful chemical energy ”.
Rather than collecting this electrical energy directly, the scientists followed an innovative approach and used the energy to break the chemical bonds in water and produce oxygen and hydrogen gas.
"This is a new phenomenon, which converts mechanical energy directly into chemical energy," says Xu, calling it the piezoelectrochemical effect (PZEC).
The chemical energy of hydrogen fuel is more stable than electrical charge, he explains. It is relatively easy to store and will not lose potency over time.
With the right technology, Xu envisions this method to be useful for generating small amounts of power from a multitude of small sources; for example, a mobile phone or music player could be charged by walking and the breeze could power the street lights.
Source: Science Daily