Game-changing energy harvester generates endless electricity from seawater

Researchers have created a new energy harvester device that may be capable of continuously generating electricity from seawater.

The Korea Institute of Machinery and Materials (KIMM) researchers developed this new harvester that depends on the natural movement of sodium ions in seawater to produce electricity.

This eco-friendly harvester has a wide range of potential applications, from powering sensors to monitoring environmental factors.

“The newly developed technology is an eco-friendly energy harvesting technology that allows continuous self-charging and can be used without external energy,” said Seungmin Hyun, Principal Researcher of the KIMM.

Components of harvester

A harvester turns waste energy into electricity.

This energy harvester consists of various components such as multi-walled carbon nanotubes and graphene oxide films. These two serve as the cathode and anode of the harvester.

Nanotubes are made from carbon atoms, which are known for their high conductivity. Moreover, the graphene oxide films consist of oxygen-containing functional groups.

Lastly, seawater is used as the electrolyte, or conductive medium, in the harvester.

As the ions in the seawater move, a potential difference is created, generating electricity.

“During this process, more cations in the electrolyte gather closer to the anode, which has a relatively higher oxygen functional group content, and a potential difference is created as a result of the rearrangement of ions between the two electrodes,” explained the press release.

More powerful than traditional ones

The new harvester is 4.2 times more powerful as compared to existing ones. It has a power density of 24.6 mW/cm³, which is significantly higher than the 5.9 mW/cm³ power density of the typical ionic hydrogel-based water-based energy generators.

Interestingly, it can power small devices such as calculators, watches, and sensors.

For generating more electrical energy, the size of the harvester can be increased or also can be linked with many harvesters together.

Hyun added: “It is expected to be used as an energy source to operate sensors and devices in environments where monitoring environmental factors (such as temperature, dissolved oxygen (DO), inorganic nitrogen in the ocean) is required.”

Unlike traditional water-based energy harvesters, this new technology doesn’t require external energy to recharge. This makes it ideal for use in remote, ocean-based applications.

Standard water-based energy harvesters are thought to have low energy conversion efficiency. Furthermore, they rely on external energy sources to maintain the circulation of water for reuse.

Therefore, these harvesters are impractical in places without a constant source of external energy for water movement.

The new harvester could be used without requiring external energy by restoring its initial open circuit voltage.

“This technology is anticipated to find applications as a source technology in a wide range of sectors including water-based energy harvesting and eco-friendly energy technologies,” the press release noted.

The findings were published in the Chemical Engineering Journal.