New hydrovoltaic cell continuously generates electricity with little water and no sunlight

A team of engineers at the Chinese Academy of Sciences has modified the approach used to generate electricity with a hydrovoltaic cell, building one that uses little water and no sunlight. Their study is published in the journal Nature Communications.

Hydrovoltaic cells generate electricity by capturing the energy from interactions between water and other surfaces. Such interactions typically rely on sunlight as the instigating power source. As the researchers with this new effort note, the traditional approach results in a hydrovoltaic cell that needs a continuous source of water and that typically only operates in dry environments. In this new study, the team in China overcame both problems to create a new kind of hydrovoltaic cell.

To allow their cell to operate in virtually any climate, the research team built their cell inside a hermetically sealed container—they call the result a hermetic hydrovoltaic cell (HHC). Inside, they placed a double-layer wicking agent made of tissue paper and carbon black. A small amount of water added to the HHC is continuously circulated due to changes in ambient temperature and capillary flow in the tissue paper.

The HHC generates power using the energy of ambient heat as the instigating power source. Testing showed the cell is capable of producing electricity for up to 160 hours without the addition of any more water. The researchers suggest such a cell would be an ideal candidate for people living in water-poor areas.

Further testing showed that exposure to strong sunlight increased electrical output. The researchers found this was due to energy from the sunlight increasing the rate of absorption by the black carbon, which in turn led to an increased moisture gradient.

The research team suggests their HHC could prove to be useful in places with limited electricity options, noting their cell is both low cost and requires little water. They also point out that its power source, ambient heat, is inexhaustible, meaning that once obtained, the cell could possibly function for as long as desired.