It is called hydrovoltaic and is based on the ability to produce electricity by exploiting the interaction of water with specific nanostructured materials. Working on this front is the Polytechnic School of Lausanne in Switzerland.
The flows of fluids and ions due to water evaporation can generate electrostatic charges by interacting with a hexagonal network of silicon nanopillars, spaced in such a way as to create microchannels for the passage of water vapor. In laboratory tests, a power density of eight microwatts per square centimeter was measured using a low-concentration saline solution.
This is very little, but the research is still in its early stages. Further developments are therefore awaited.
