QAZAQ GREEN. Chinese researchers say they have found a way to continuously produce electricity from water within a sealed container, drawing heat from the surrounds to create vapour for power generation, SCMP reports.

While solar-based hydrovoltaic cells need sunlight to work, the team from the Chinese Academy of Sciences say their cell does not – and its resistance to wind and humidity means it could be used in harsh environments like deserts and in the dark.

“We fabricate a hermetic hydrovoltaic cell (HHC) to harvest ambient heat and have fully addressed the limitations posed by environmental conditions,” the team wrote in a paper published in peer-reviewed journal Nature Communications on November 12.

“We anticipate that the hermetic hydrovoltaic cell and the internal circulation hydrovoltaic effect enables the generation of electricity with low cost, easy accessibility, and wide applicability.”

They said their cell achieved stable electricity output for 160 hours with negligible water consumption, which could make it a good candidate for extreme environments like water-scarce deserts, humid tropical rainforests and underground engineering sites.

Hydrovoltaic electricity generation – which captures energy from the interaction of water with surfaces – is a source of green energy that can help reduce reliance on fossil fuels.

But the application of hydrovoltaic generators has been limited by environmental conditions such as light and wind. The team said current hydrovoltaic approaches require low humidity to function and they continuously consume water.

To overcome these challenges, the researchers designed a sealed cell with an internal electricity generation unit made from carbon black and tissue paper to allow for capillary action.

“The slight fluctuations in ambient temperature and the designed heterogeneous wicking bilayer enable the continuous evaporation and capillary flow inside the hermetic cell, forming [a] water circulation process,” the team wrote.

Ambient heat, which is an inexhaustible low-grade energy source, is harnessed through the capillary evaporation and outputted in the form of electricity.

“Although the HHC exhibits a moderate open-circuit voltage, considering its zero-water consumption, it still possesses the highest energy conservation efficiency,” the researchers said.

The team said they had discovered a previously unknown internal circulation hydrovoltaic effect by investigating the energy harvesting capability within their cell.

The study also found that perpetual temperature fluctuations – which are usually detrimental during energy harvesting – could allow for stable energy generation using closed-loop circulation within a cell.

“It is anticipated that the universal applicability, the stable output, and the non-consumption make the HHC and this sustainable water circulation strategy efficient for a wide variety of situations,” the researchers said.

“Moreover, the constructed water circulation system as well as the associated energy conversion processes would definitely inspire the innovative design of diverse devices.”