With each passing day, scientists are coming out with unique solutions to lessen our dependence on fossil fuels. They are now thinking of turning stray forms of energy such as noise or random vibrations from the environment into useful form of energy. They want to use piezoelectric effect for such purposes. Some materials produce electricity while undergoing mechanical stress. This is known as piezoelectric effect. Small piezoelectric crystals can come up with enough voltage to create a spark which can be utilized to ignite gas.
Piezoelectric crystals act as igniters. They are helpful in many gas-powered appliances like ovens, grillers, room heaters, and hot water heaters. These piezoelectric crystals are quite tiny and can be easily fitted into lighters too. Piezoelectric crystals are also fitted into electronic clocks and watches for time alarm noise.
Materials scientists at the University of Wisconsin-Madison have taken the help of piezoelectric effect to harness random energy available in the atmosphere to turn water into usable hydrogen fuel. It might prove a simple, efficient method to recycle waste energy. The research team is led by Huifang Xu, who is a UW-Madison geologist and crystal specialist. They took nanocrystals of zinc oxide and barium titanate. These two nanocrystals were put in water. When these crystals received ultrasonic vibrations, the nanofibers flexed and catalyzed a chemical reaction. This whole process resulted in splitting the water molecules into hydrogen and oxygen.
Huifang Xu along with his team has published their work in the Journal of Physical Chemistry Letters. They wrote in the journal, “This study provides a simple and cost-effective technology for direct water splitting that may generate hydrogen fuels by scavenging energy wastes such as noise or stray vibrations from the environment. This new discovery may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.”
Xu and his colleagues applied the piezoelectric effect to the nanocrystal fibers successfully. Xu says, “The bulk materials are brittle, but at the nanoscale they are flexible.” It is akin to the difference between fiberglass and a pane of glass.
It has been noted that smaller fibers exhibit more flexibility than larger crystals. Therefore smaller fibers can generate electric charges without difficulty. The project team has extracted an impressive 18 percent efficiency with the nanocrystals, higher than most experimental energy sources. Xu shares his views, “because we can tune the fiber and plate sizes, we can use even small amounts of [mechanical] noise — like a vibration or water flowing — to bend the fibers and plates. With this kind of technology, we can scavenge energy waste and convert it into useful chemical energy.” What a fantastic idea.
But scientists didn’t utilize this electrical energy straightaway. They use this energy in breaking the chemical bonds in water to split oxygen and hydrogen. Xu explains, “This is a new phenomenon, converting mechanical energy directly to chemical energy.” Xu calls it a piezoelectrochemical (PZEC) effect. Why it seems that scientists are beating around the bush? Because chemical energy of hydrogen fuel is more stable than the electric charge. Storage of hydrogen fuel is easy and would not lose potency over time.
With the right technology, Xu foresees this method to be utilized where small amount of power is needed. Now we can imagine charging a cell phone while taking our morning walk or we can enjoy cool breeze that can power street lights. Xu says, “We have limited areas to collect large energy differences, like a waterfall or a big dam. But we have lots of places with small energies. If we can harvest that energy, it would be tremendous.”