Harnessing the immense power of the oceans could satiate all the world’s electricity needs. Attempts to do that have been ongoing for years, and some technologies are on their way to being deployed on a large scale. But the more technologies we have, the better.
In a study published in the journal One Earth, researchers now present a novel way to generate electricity from ocean waves. The snake-like device is built of generators that rely on static electricity to produce power as they float and undulate on the surface of water.
The oceans are the biggest source of renewable energy on earth. Many different prototypes to harness waves, tides, and ocean currents have been developed over the years. Some float on the surface, others are submerged just below, while still others are tethered to the ocean floor.
But these wave energy technologies are more expensive than wind and solar, and have yet to be proven on a large scale over a long time. Most of them use wave action to push magnets through coils, which is bulky, expensive, and inefficient.
The team from the Chinese Academy of Sciences in Beijing built a device that produces power by tapping into the buildup of charge when two different surfaces rub against each other. This phenomenon, called the triboelectric effect, is what causes static electricity. Researchers have used it to make solar cell coatings that generate electricity when rain or snow hits them.
The new idea to use triboelectric generators for wave power comes from Zhong Lin Wang, who made the first triboelectric generator a decade ago. These generators are small, and have typically been proposed for powering sensors, wearable electronics, and small gadgets. But connecting thousands of generators together should produce enough power for larger uses. Several designs have been proposed for this.
In the new paper, Wang and his colleagues propose a design that generates twice the amount of power per unit volume as previously reported systems. It consists of a spring-like coil inside a cylinder. As the cylinder rolls back and forth on waves, the different parts of the spiral touch and separate, generating current.
Laboratory tests showed that the device produced up to 347 watts of power per cubic meter, 30 times as much as other triboelectric designs for harvesting wave energy.
There wear and tear of the coils due to friction is an issue that still needs to be resolved. Larger real-world tests will show whether the device can withstand the ocean’s fury.
Source: Wei Yuan et al. Anaconda-shaped spiral multi-layered triboelectric nanogenerators with ultra-high space efficiency for wave energy harvesting. One Earth2022.