A team of researchers from the University of Wisconsin-Madison have just discovered that crystals of zinc oxide, if submerged, absorb its vibrations and act like a piezoelectric material, developing areas of strong negative and positive charges.
You can imagine what happens next: these charges dissociate the surrounding water molecules into hydrogen and oxygen.
“This is like a free lunch,” says lead researcher Huifang Xu. “You are getting energy from the environment just like solar cells capture energy from the sun.” Xu called the process the “piezoelectrochemical” effect.
For getting the crystals, the team grew thin microfibers of highly flexible zinc oxide crystals, which vibrate easily on sound waves. An ultrasonic sound, for example, was discovered by the researchers to cause the fibers to bend between 5 and 10 degrees at each end, creating a voltage between them.
Fibers of different sizes absorb different types of vibrations best. Knowing this, the scientists can tune the fibers to maximize the energy production.The zinc oxide material Xu and his team created convert water into gas with an 18% efficiency, while normal piezoelectric materials do it with at most 10 percent.
“It’s a good idea,” says Jinhui Song of Georgia Tech University, Atlanta. Because there is no need to create a circuit, devices based on the new crystals could be simpler than those based on conventional dry piezoelectrics, he points out. “They can reduce the complexity of the device.”
Getting energy from water has been the dream of many for decades, but even if the process is simple, it’s not as efficient as it looks. Running an electrolysis on water and getting hydrogen out of the process eats more energy than you would get by burning the hydrogen. That’s the reason why people are looking for ways to generate hydrogen so cheaply that the lack of efficiency doesn’t matter that much. Hydrogen would be the ultimate fuel, the perfect solution in terms of cleanliness, even compares to batteries, because by burning or passing it through a fuel cell only gets you water.