Plugging into ocean waves with a flexible, seaweed-like generator

Date:
October 20, 2021
Source:
American Chemical Society
Summary:
Ocean waves can be powerful, containing enough energy to push
around sand, pebbles and even boulders during storms. These waves,
as well as smaller, more gentle ones, could be tapped as a source
of renewable energy. Now, researchers have developed flexible
power generators that mimic the way seaweed sways to efficiently
convert surface and underwater waves into electricity to power
marine-based devices.



FULL STORY ========================================================================== Ocean waves can be powerful, containing enough energy to push around sand, pebbles and even boulders during storms. These waves, as well as smaller,
more gentle ones, could be tapped as a source of renewable energy. Now, researchers reporting in ACS Nano have developed flexible power generators
that mimic the way seaweed sways to efficiently convert surface and
underwater waves into electricity to power marine-based devices.


========================================================================== Across many coastal zones, networks of sensors collect information
on the water's currents, tides and clarity to help ships navigate and
to monitor water quality. This "marine internet of things" is powered
mostly by batteries that have to be replaced from time to time, which
is time-consuming and expensive.

Wind and solar power could be used, but they aren't suitable for
underwater applications. Looking to harness the ocean's continuous
movement as a renewable energy source, researchers initially developed
floating devices that converted wave energy into electricity using
rotating magnets. But these devices were inefficient with less frequent
waves, such as those found underwater.

Triboelectric nanogenerators (TENGs), which rely on surfaces coming in
contact to produce static electricity, could be a way to address this
challenge because of their effectiveness for harvesting low-frequency, low-amplitude wave energy.

So, Minyi Xu, Zhong Lin Wang and colleagues were inspired by plants living
on the seafloor to create flexible TENGs. The researchers wanted to copy
the way strands of seaweed vibrate to charge bendable triboelectric
surfaces, harvesting the movement of waves into electricity to power
floating and submerged marine sensors.

To make the triboelectric surfaces, the researchers coated 1.5-inch
by 3-inch strips of two different polymers in a conductive ink. Then
a small sponge was wedged between the strips, creating a thin air gap,
and the whole unit was sealed, creating a TENG. In tests, as the TENGs
were moved up and down in water, they bent back and forth, generating electricity. When the researchers put the TENGs in water pressures
similar to those found underwater in coastal zones, they found that
the air gap between the two conductive materials decreased. However,
the devices still generated a current at 100 kPa of pressure -- the same pressure that typically exists at a 30-foot water depth where there is
almost no underwater wave movement. Finally, the researchers used a
wave tank to demonstrate that multiple TENGs could be used as a mini
underwater power station, supplying energy for either a thermometer,
30 LEDs or a blinking miniature lighthouse LED beacon. The researchers
say their seaweed- like TENG could reduce the reliance on batteries in
coastal zones, including for marine sensors.

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yan Wang, Xiangyu Liu, Yawei Wang, Hao Wang, He Wang, Steven
L. Zhang,
Tiancong Zhao, Minyi Xu, Zhong Lin Wang. Flexible Seaweed-Like
Triboelectric Nanogenerator as a Wave Energy Harvester
Powering Marine Internet of Things. ACS Nano, 2021; DOI:
10.1021/acsnano.1c05127 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211020135844.htm

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